d)CU~-.'-,)^'^Xa  ■f-'^ 


Issued  August  8,  1911. 

U.  S.  DEPARTMENT  OF  AGRICULTURE. 

BUREAU  OF  ANIMAL  INDUSTRY.— Bulletin  142. 
A.  D.  MELVIN,  Chief  of  Bureau. 


■  DOURINE  OF  HORSES: 


ITS  CAUSE  AND  SUPPRESSION. 


BY 


JOHN  R,  MOHLER,  V.  M.  D., 
Chief  of  the  Pathological  Division . 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1911. 


Issued  August  3,  lyu. 

U.  S.  DEPARTMENT  OE  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY— Bulletin  142. 
A.  D.  MELVIN,  Chief  of  Burkau. 


DOURINE  OF  HORSES: 

ITS  CAUSE  AND  SUPPRESSION. 


BY 

JOHN  R.  MOHLER,  V.  M.  D., 

Chief  of  the  Pathological  Division 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1911. 


THE  BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  A.  D.  Melvin. 

Assistant  Chief:  A.  M.  Farrington.  • 

Chief  Clerk:  Charles  C.  Carroll. 

Animal  Husbandry  Division:  George  M.  Rommel,  chief. 
Biochemic  Division:  M.  Dorset,  chief. 
Dairy  Division:  B.  H.  Rawl,  chief. 

Inspection  Division:  Rice  P.  Steddom,  chief;  R.  A.  Ramsay,  Morris  Wooden, 
and  Albert  E.  Behnke,  associate  chiefs. 

Pathological  Division:  John  R.  Mohler,  chief.  y 

Quarantine  Division:  Richard  W.  Hickman,  chief. 
Zoological  Division:  B.  H.  Ransom,  chief. 
Experiment  Station:  E.  C.  Schroeder,  superintendent. 
Editor:  James  M.  Pickens. 


LETTER  OF  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Animal  Industry, 

Washington,  D.  C,  July  6,  1911. 
Sir:  I  have  the  honor  to  transmit  herewith  and  to  recommend 
for  pubHcation  as  a  bulletin  of  this  bureau  a  manuscript  entitled 
"Dourine  of  Horses:  Its  Cause  and  Suppression,"  by  Dr.  John  R. 
Mohler,  Chief  of  the  Pathological  Division. 

Respectfully,  A.  D.  Melvin, 

Chief  of  Bureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture. 


Digitized  by  the  Internet  Archive 

in  2007  with  funding  from 

IVIicrosoft  Corporation 


http://www.archive.org/details/dourineofhorsesiOOmohliala 


CONTENTS. 


Page. 

Introduction : 7 

Nomenclature 8 

History 8 

Definition 10 

Cause 10 

Trypanosoma  equiperdum 11 

Cultivation  of  the  trypanosome 13 

Searching  for  the  trypanosomes 15 

Infectiveness 17 

Symptoms 27 

Post-mortem  lesions 29 

Course  of  the  disease 31 

Prognosis 31 

Differential  diagnosis 32 

Treatment 34 

Method  of  eradication 35 

5 


ILLUSTRATIONS. 


Plate  I.  Fig.  1. —  Trypanosoma  equiperdum  from  plaque  on  mare  79.    Fig.  2.— 

Trypanosoma  equiperdum  from  a  culture 12 

II.  Fig.  1. — Percheron  stallion  42  showing  condition  at  the  time  of  pur- 
chase.    Fig.  2. — Same  stallion  after  dourine  had  developed 18 

III.  Fig.  1. — Percheron  mare  80  showing  chronic  dourine.     Fig.  2. — Mare 

47  in  the  last  stage  of  dourine 18 

IV.  Fig.  1. — Mare  80  affected  with  dourine,  showing  paralysis  of  the  right 

nostril.     Fig.  2. — Lesions  of  dourine  involving  the  external  genitals 

and  perineum  of  mare  47 28 

V.  Mare  79,  bred  to  an  imported  stallion  March  7,  1911,  and  developed 

evidences  of  dourine  15  days  later 28 

6 


DOURINE  OF  HORSES:  ITS  CAUSE  AND  SUPPRESSION. 


INTRODUCTION. 

On  May  27,  1911,  the  Bureau  of  Animal  Industry  received  a  letter 
from  Dr.  J.  I.  Gibson,  State  veterinarian  of  Iowa,  stating  that  there 
was  in  Taylor  County  an  outbreak  of  a  disease  suspected  of  being 
dourine,  and  requesting  that  an  expert  be  sent  to  make  an  investiga- 
tion. The  disease  had  been  reported  by  Dr.  A.  H.  Quin,  a  practitioner 
of  Creston,  Iowa,  and  his  diagnosis  was  subsequently  confirmed  on 
the  part  of  the  bureau  by  Drs.  A.  D.  Melvin,  E.  T.  Davison,  and  the 
writer,  who  were  of  the  unanimous  opinion  that  the  symptoms  and 
lesions  manifested  were  the  most  typical  of  any  of  the  cases  they  had 
observed.  Three  of  the  affected  mares  were  at  once  purchased  and 
sent  to  Washington  for  experimental  purposes.  After  a  careful  and 
prolonged  examination  of  almost  200  slides,  six  living,  wriggling 
trypanosomes,  Trypanosoma  equiperdum,  were  found  on  June  28, 
19 11,  by  the  writer  in  the  blood-tinged  serum  obtained  from  a  recently 
developed  plaque  on  the  abdomen  of  one  of  the  mares  (No.  79),  thus 
confirming  the  diagnosis  and  also  establishing  the  identity  of  the  dis- 
ease with  that  of  Asia,  Africa,  and  Continental  Europe.  This  is  the  first 
discovery  of  the  Trypanosoma  equiperdum  in  the  natural  cases  of  dourine 
in  the  United  States,  although  in  1903  considerable  work  was  done  with 
this  trypanosome  imported  from  France  and  subsequently  inoculated 
into  horses  at  the  Bethesda  Experiment  Station.  Previous  to  1911 
there  had  been  no  authentic  case  of  dourine  reported  among  the 
horses  of  this  country  since  1906,  although  there  had  been  a  number 
of  alleged  or  suspected  cases  brought  to  the  bureau's  attention  from 
time  to  time  which  demanded  a  full  investigation,  but  always  with 
negative  results.  The  object  of  this  paper  is  therefore  not  only  to 
describe  the  methods  which  have  been  employed  in  suppressing  this 
insidious  disease  of  horses  but  also  to  furnish  such  a  description  of 
the  symptoms  and  lesions  as  to  make  it  easier  to  differentiate  dourine 
from  other  diseases  which  may  simulate  it.  The  chronicity  of  the 
affection,  its  ultimate  fatal  results,  and  the  valuable  breeding  animals 
which  are  usually  attacked,  make  it  of  considerable  economic  sig- 
nificance and  render  its  early  recognition  and  the  subsequent  enforce- 
ment of  prophylactic  measures  extremely  important  to  the  horse 
breeder  and  the  sanitarian. 

7 


8  DOURINE   OF   HORSES:    ITS   CAUSE   AND   SUPPRESSION. 

NOMENCLATUBE. 

This  disease  has  been  described  under  various  names,  according  to 
the  country  in  which  it  is  found,  chief  among  which  may  be  mentioned 
"el  dourine,"  "maladie  du  coit,"  covering  disease,  equine  syphihs, 
genital  glanders,  breeding  paralysis,  chancrous  epizootic,  epizootic 
paraplegia,  and  "beschalkrankheit."  The  most  commonly  employed 
name  for  this  affection  in  the  United  States  is  the  short  and  distinctive 
term  "dourine,"  which  is  taken  from  the  Ai-abic,  meaning  "unclean." 

HISTORY. 

The  primeval  home  of  the  malady  is  supposed  to  be  in  Asia,  where 
it  is  considered  to  have  existed  for  centuries.  It  was  first  definitely 
described  in  1796  by  Ammon  as  occurring  among  the  animals  belong- 
to  the  sovereign  of  Prussia  at  Trakehnen.  During  the  first  half  of 
the  nineteenth  century  it  was  described  as  occurring  in  many  coun- 
tries of  Europe,  including  Germany,  France,  Austria,  and  Switzer- 
land. It  was  also  known  to  be  prevalent  along  the  northern  region 
of  Africa  in  Algiers.  It  is  supposed  to  have  been  introduced  during 
the  early  part  of  the  nineteenth  century  into  Continental  Europe 
through  the  importation  of  breeding  horses,  especially  Arab  stallions, 
from  the  Orient. 

In  the  United  States  the  disease  was  first  suspected  in  1885  and 
recognized  in  1886  by  Dr.  W.  L.  Williams,  who  was  then  a  practi- 
tioner at  Bloomington,  111.  The  infection  was  traced  to  a  Percheron 
stallion,  imported  from  France  in  1882,  which  had  a  brand  mark 
under  the  mane  very  much  resembling  the  letter  D  (dourine  ?).  It  is 
supposed  that  he  was  affected  with  the  disease  and  had  been  branded 
in  France  before  being  transported  to  this  country.  The  nature  of 
the  disease  not  being  at  first  recognized,  its  dissemination  occurred 
before  attention  was  attracted  to  it.  The  State  of  Illinois,  however, 
took  hold  of  the  outbreak  and  as  a  result  of  rigid  prophylactic  meas- 
ures the  disease  was  eradicated  from  the  State  in  1888,  but  not 
before  an  affected  stallion  had  been  shipped  to  Gordon,  Nebr., 
thereby  starting  up  a  new  center  of  infection  in  that  locahty. 

In  1892  dourine  was  again  brought  into  public  notice  by  the  appear- 
ance of  an  outbreak  among  the  breeding  horses  of  northwestern 
Nebraska,  the  history  of  which  suggested  that  it  originated  with  this 
Gordon  stallion.  An  inspector  of  the  Bureau  of  Animal  Industry 
investigated  the  outbreak  and  found  that  upward  of  200  mares  and 
stallions  were  affected  with  the  disease.  Steps  for  the  eradication 
of  this  outbreak  were  begun  in  June,  1893,  at  which  time  some  of 
the  diseased  animals  had  died,  and  the  breeders  were  using  all  the 
precautions  possible  to  prevent  its  spread.  Under  the  authority  of 
the  Secretary  of  Agriculture  all  diseased  animals  still  alive,  including 
32  in  Nebraska  and  5  in  South  Dakota,  were  purchased  and  destroyed. 


NOMENCLATUKE HISTORY.  9 

After  an  expenditure  of  about  $5,500  the  disease  was  considered  to 
have  been  eradicated  from  that  section  of  the  country.  Five  years 
later  the  infection  again  made  its  appearance  in  the  same  portion 
of  Nebraska,  and  early  in  1899  the  bureau  again  began  the  work  of 
eradication.  Many  inspections  were  made  and  those  animals  wliich 
were  found  diseased  were  purchased  and  killed.  Many  obstacles 
were  encountered  and  the  disease  evidently  kept  smoldering  during 
1900. 

In  1901  the  infection  appeared  with  increased  vigor,  this  time  in 
the  Pine  Ridge  and  Rosebud  Indian  Reservations  in  South  Dakota, 
in  addition  to  northern  Nebraska,  and  more  stringent  measures  were 
immediately  inaugurated  to  control  the  spread  of  the  disease.  During 
the  next  year  10  diseased  stallions  and  76  diseased  mares  were  pur- 
chased and  slaughtered  and  29  diseased  stallions  were  castrated. 
However,  eradication  in  tliis  region  was  extremely  difficult,  owing  to 
the  wild  condition  of  the  country  as  well  as  of  the  horses  and  from 
the  fact  that  many  horse  owners  would  try  to  conceal  from  the  in- 
spectors animals  wliich  they  knew  to  be  affected  with  the  disease. 
Tliis  reappearance  of  the  disease  among  horses  in  Nebraska  and  South 
Dakota  after  it  apparently  had  been  stamped  out  caused  a  thor- 
ough investigation  of  its  latent  qualities  and  other  peculiarities,  and 
as  a  result  Veterinary  Inspectors  E.  T.  Davison  and  W.  J.  Fretz 
were  stationed  at  Rushville,  Nebr.,  with  instructions  to  prosecute 
vigorously  the  work  of  eradication.  In  1903  there  were  16,287  horses 
inspected,  of  wliich  511  were  found  diseased  and  were  killed,  while 
1,899  stallions  were  castrated.  Careful  and  vigorous  work  was  con- 
tinued in  this  way,  with  the  result  that  8,705  horses  were  inspected 
in  1905,  but  only  1  stalHon  and  8  mares  were  found  suspicious  and 
destroyed  and  9  stallions  castrated. 

During  the  year  1903  dourine  was  reported  in  Van  Buren  County, 
Iowa,  and  steps  were  immediately  taken  to  stamp  it  out.  As  a  result 
410  horses  were  inspected,  2  exposed  stalUons  were  castrated,  and  18 
mares  slaughtered.  No  connection  could  be  estabHshed  between  this 
outbreak  and  that  in  Nebraska,  but  it  was  quite  defi^nitely  determined 
that  an  imported  Percheron  stallion  purchased  by  a  company  of 
farmers  was  responsible  for  its  appearance. 

In  1906  the  last  suspicious  cases  of  dourine — 1  stalHon  and  2  mares — 
were  destroyed  in  South  Dakota,  and  sufficient  time  has  since  elapsed 
to  warrant  confidence  that  the  disease  has  been  completely  eradicated 
from  that  section  of  the  United  States. 

In  Canada  the  presence  of  dourine  was  discovered  by  Dr.  Burnett 
in  1904,  and  the  causative  trypanosome  was  demonstrated  by  Dr. 
Watson  in  1907,  from  the  vulva  of  a  mare.  From  the  occurrence  of 
this  disease  until  the  latest  available  published  report  in  1909,  628 
animals  were  purchased  and  destroyed.  A  marked  diminution  in 
the  number  of  infected  animals  is  apparent  in  the  report,  and  the  dis- 
ease is  said  to  be  under  control. 
834°— Bull.  142—11 2 


10  DOUBINE   OF   HORSES  :   ITS   CAUSE   AND   SUPPRESSION. 

As  already  stated,  an  outbreak  of  dourine  has  recently  (June,  1911) 
been  located  in  Taylor  County,  Iowa,  where  4  stallions  have  been 
found  aflfected  and  5  exposed  to  this  disease.  One  of  the  former 
stallions  has  since  died  of  the  infection.  In  addition,  5  mares  have 
sho^\^l  symptoms  of  dourine,  1  of  which  subsequently  died  of  the 
disease,  9  are  suspicious  cases,  and  94  have  been  exposed,  but  at 
present  show  no  evidence  of  infection.  These  diseased  animals,  to- 
gether with  all  exposed  stallions  and  mares,  were  immediately  quaran- 
tined by  the  State.  Those  showing  lesions  of  the  disease  were  pur- 
chased by  the  Government  and  destroyed,  while  the  exposed  animals 
are  still  in  quarantine  under  observation.  Several  Federal  and  State 
inspectors  are  making  farm-to-farm  inspections  with  the  view  of  dis- 
covering any  latent  or  hidden  cases,  and  it  is  now  beUeved  that  the 
infection  is  entirely  under  control.  The  source  from  which  this  center 
of  infection  was  derived  is  only  a  matter  of  conjecture,  but  there  is 
apparently  no  connection  between  this  and  any  of  the  previous  out- 
breaks. No  authentic  information  as  to  the  origin  of  the  outbreak 
has  been  discovered  up  to  the  present  time,  but  all  cases  lead  back  to 
a  Percheron  stallion,  which  was  imported  in  1909  and  brought  direct  to 
Lenox,  Iowa.  The  possibility  of  such  animals  bringing  the  infection 
into  this  country  must  be  apparent  from  the  following  explanation. 

Schneider  and  Buffard  maintain  that  in  France  dourine  appears 
nearly  every  year  in  the  Department  of  Basses-Pyrenees  on  the 
Spanish  frontier.  It  is  stated  that  mares  get  infected  by  the  asses  or 
horses  by  which  they  are  covered.  It  is  the  custom  to  have  a  mare 
first  covered  by  an  ass,  and  if  not  impregnated  she  is  then  served  by 
a  stallion.  The  asses  operate  on  both  sides  of  the  frontier,  and  in 
this  way  introduce  the  disease  into  France  from  Spain,  where  it  has 
been  known  to  occur  for  years,  especially  in  Navarre. 

DEFINITION. 

Dourine  is  a  specific  infectious  disease  affecting  under  natural  con- 
ditions only  the  horse  and  the  ass,  transmitted  from  animal  to  animal 
by  the  act  of  copulation,  and  due  to  a  single-celled  animal  parasite  or 
protozoan,  the  Trypanosoma  equiperdum.  It  is  characterized  by  an 
irregular  incubation  period,  the  confinement  of  the  first  symptoms 
to  the  genital  tract,  the  chronic  course  which  it  runs,  and  by  finally 
producing  complete  paralysis  of  the  posterior  extremities,  with  a  fatal 
termination  in  from  six  months  to  two  years. 

CAUSE. 

Many  widely  different  theories  as  to  the  exact  cause  of  this  affection 
have  existed  and  been  advocated  in  the  past  50  years.  The  fact  that 
the  disease  spread  from  animal  to  animal  in  certain  centers  of  infec- 
tion, and  that  large  horse-breeding  districts  and  countries  which  did 


CAUSE.     '  11 

not  import  any  breeding  animals,  such  as  New  Zealand,  Australia, 
England,  and  South  America,  remained  free  from  the  disease,  showed 
it  to  be  of  an  infectious  nature.  Investigations  by  Thanhoffer 
resulted  in  his  obtaining  bacilli,  cocci,  and  streptococci  from  the 
blood  and  nervous  system  of  animals  dead  of  this  disease.  However, 
none  of  these  organisms  were  invariably  present,  and  from  the  fact 
that  the  disease  was  confined  almost  exclusively  to  breeding  animals 
and  seemed  to  be  transmitted  solely  through  the  act  of  copulation 
doubt  arose  as  to  the  likelihood  of  any  vegetable  organisms  being  the 
causal  agent  in  its  production  and  dissemination.  At  one  time  it  was 
considered  to  be  identical  with  human  syphilis  and  was  thought  to 
be  conveyed  from  man  to  asses  and  mares,  but  the  fallacy  of  this  belief 
was  demonstrated  by  Haussman  and  Knauert. 

As  opposed  to  the  theory  of  coition  pla3dng  the  entire  part  as  a 
means  of  transmission  of  the  disease,  we  have  the  statements  of 
Hayne  and  Haxthusen,  who  have  reported  the  disease  in  geldings 
and  also  in  mares  which  have  never  had  sexual  intercourse  with  the 
stallion.  It  may  be  also  transmitted  with  ease  artificially  by  means 
of  inoculation  into  horses,  dogs,  rabbits,  rats,  and  other  susceptible 
animals,  with  relatively  large  quantities  of  the  blood  and  membranes 
of  certain  organs  of  animals  affected  with  the  disease.  However, 
sexual  intercourse  is  by  far  the  most  common  means  of  transmission, 
and  if  other  means  do  exist  they  are  so  rare  that  they  have  little  or 
no  practical  importance  in  the  adoption  of  measures  for  the  suppres- 
sion of  the  disease. 

It  was  not  until  1896  that  the  true  cause  of  the  malady  was  dis- 
covered by  Rouget,  but  his  work  was  neither  credited  nor  confirmed 
until  1899.  At  this  time  two  French  army  officers,  Schneider  and 
Buffard,  proved  that  trypanosomes  were  associated  in  causal  relation 
to  the  disease,  by  successful  inoculations  of  animals  with  organisms 
from  an  infected  stallion.  Later  Nocard  verified  these  results,  and 
subsequently,  in  1901,  Laveran  and  Mesnil  carefully  described  the 
trypanosome,  naming  it  Trypanosoma  rougeti  after  its  discoverer, 
although  it  had  previously  been  named  by  Doflein,  Trypanosoma 
equiperdum. 

TRYPANOSOMA    EQUIPERDUM. 

This  trypanosome  is  a  unicellular  animal  jjarasite  (flagellate)  very 
closely  resembhng  the  numerous  other  varieties  of  trypanosomes 
which  have  during  the  last  few  years  been  proved  to  be  the  causes 
of  several  tropical  diseases  of  animals,  chief  of  which  may  be  men- 
tioned surra,  nagana,  and  mal  de  caderas.  When  taken  from  the 
blood  of  an  infected  animal  it  is  a  somewhat  spindle-shaped  organism 
with  the  posterior  extremity  bluntly  conical;  anteriorly  (the  head)  it 
is  prolonged  into  a  long,  wavy,  whiplike  flagellum,  giving  the  appear- 


12  DouBiNE  OF  horses:  its  cause  and  suppression. 

ance  of  a  tail,  thus  apparently  reversing  the  true  position  of  the  tail 
and  head.  (See  PI.  I,  fig.  1.)  Along  one  side  is  a  wavy,  undulating, 
flangelike  membrane  terminating  in  the  flagellum.  The  nucleus  is 
large  and  located  centrally,  wliile  the  centrosome  or  kinetonucleus  is 
situated  posteriorly,  and  is  the  starting  point  of  the  undulating 
membrane  and  flagellum.  The  trypanosome  is  actively  motile,  but 
not  so  much  so  as  certain  other  forms  found  in  rats.  Motion  may 
occur  indiscriminately  forward  or  backward  by  the  rapid  lasMng 
movements  started  in  the  flagellum  and  continued  in  the  vibratory 
movements  of  the  undulating  membrane;  also  by  the  contraction 
of  the  protoplasm  of  the  body.  The  size  varies  from  25  to  30  microns 
in  length  by  about  2  microns  thick. 

The  most  satisfactory  way  of  determining  the  presence  of  these 
parasites  is  to  examine  fresh  preparations  of  the  suspected  fluid 
spread  in  a  thin  layer  on  a  slide,  covered  with  a  cover  slip  and  viewed 
with  a  4-millimeter  objective  and  No.  4  ocular.  The  trypanosomes 
may  be  readily  stained  and  their  structure  brought  out  well  by 
Giemsa's  azur-eosin  stain,  Nocht's  modification  of  Romanowsky's 
method,  or  by  Borrel's  blue. 

In  order  to  make  a  complete  study  of  this  protozoan  as  it  exists 
in  France  and  Algiers,  a  small  dog  was  imported  by  the  writer  for 
the  bureau  in  1903  after  being  inoculated  in  Prof..  Nocard's  labo- 
ratory at  the  Alfort  Veterinary  School  with  blood  infected  with 
Trypanosoma  equiperdum.  This  animal  arrived  safely  in  this  country 
in  an  apparently  healthy  condition,  giving  rise  to  apprehensions  as 
to  the  success  of  the  inoculation.  In  a  few  weeks,  however,  it  began 
to  show  signs  of  illness.  The  temperature  rose  to  103°  F.;  the 
sheath  and  the  inside  of  the  thigh  became  swollen  and  edematous. 
These  swellings  at  first  would  disappear  for  a  day  or  two,  only  to 
recur  over  a  larger  area.  The  animal  became  considerably  emaciated, 
the  edematous  swellings  spread,  involving  the  whole  inner  surface  of 
the  thighs,  as  well  as  the  entire  length  of  the  sheath,  the  appetite 
became  poor,  and  the  animal  died  in  November,  about  6  weeks  after 
its  arrival  or  8  weeks  after  the  inoculation.  During  the  life  of  the 
dog  after  the  first  appearance  of  symptoms  microscopic  examinations 
were  made  daily  of  the  blood  taken  from  the  peripheral  circulation 
as  well  as  from  the  serum  in  the  edematous  areas  about  the  genitals 
for  the  purpose  of  recording  the  trypanosomes  present,  but  they 
were  always  extremely  scarce.  After  death  these  organisms  were 
found  in  great  numbers  in  the  heart,  blood,  lungs,  fiver,  kidneys, 
and  spleen. 

It  was  with  the  trypanosomes  obtained  from  this  dog,  kept  afive 
by  continued  passage  through  white  rats,  rabbits,  dogs,  and  horses, 
that  most  of  our  work  with  the  organism  has  been  done.  White 
rats  were  by  far  the  most  satisfactory  experiment  animals  for  the 


Bui.  142,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  1. 


Fig.  1  .—Trypanosoma  Equiperdum  from  Plaque  on  Mare  79.    (Composite  Drawing.) 


AHaFntCaOaliin 


Fig.  2.— Trypanosoma  Equiperdum  from  a  Culture. 


CAUSE.  13 

propagation  of  the  organism,  as  it  proved  much  more  pathogenic 
for  them,  death  usually  occurring  in  from  2  to  6  months  after 
inoculation.  The  trypanosomes  were  also  more  readily  recovered 
from  these  animals.  Although  rabbits  after  inoculation  l3ecame  grad- 
ually emaciated  and  finally  died  in  from  2  to  8  months,  it  was  only 
by  long  and  careful  microscopic  examination  that  any  trypanosomes 
could  be  found  in  their  viscera  after  death. 

The  length  of  time  which  this  protozoan  lives  when  kept  in  blood 
or  body  fluids  taken  from  the  dead  animals  varies  considerably,  but 
is  generally  stated  as  being  a  very  short  time.  Thus  Rouget  observed 
it  to  keep  its  motility  for  18  hours,  but  never  after  24  hours.  In  the 
blood  of  the  French  dog,  as  well  as  in  physiologic  salt  solution  emul- 
sions of  the  liver  and  spleen,  the  parasites  were  actively  motile  on 
the  second  day,  a  few  were  still  observed  on  the  third  day,  but  on 
the  fourth  day  none  could  be  found,  showing  that  all  were  destroved 
between  72  and  96  hours  after  the  death  of  the  host. 

CULTIVATION   OF   THE    TBYPANOeOME. 

The  attempts  at  cultivation  of  this  organism  were  attended  with 
a  great  many  difficulties,  as  it  was  rarely  possible  to  obtain  the 
organisms  in  sufficient  concentration  to  get  more  than  a  few  try- 
panosomes in  each  tube  of  media.  Contaminations  were  also  fre- 
quent, as  hanging  drop  preparations  made  under  perfectly  sterile 
precautions  from  the  blood  and  organs  of  the  rats  showed  bacteria 
in  numerous  cases  within  one-half  hour  after  death.  The  media  also 
had  to  be  made  up  fresh  continually,  as  the  water  of  condensation 
dried  out  and  the  color  of  the  blood  in  the  media  rapidly  became 
dark,  due  to  the  breaking  up  of  the  hemoglobin,  after  which  change 
the  material  was  of  little  value  for  the  growth  of  the  parasite.  The 
medium  used  in  these  experiments  was  blood  agar  prepared  after  the 
method  suggested  and  used  by  Novy  and  McNeal. 

Rabbits'  blood  was  used  throughout  the  experiments.  The  blood 
was  drawn  from  the  carotid  artery  through  a  sterilized  glass  tube 
into  sterile  potato  tubes  containing  sterile  beaters  with  which  the 
blood  was  defibrinated.  More  satisfactory  results  were  afterwards 
obtained  with  less  danger  of  contamination  by  securing  all  the  blood 
in  one  flask.  The  sterile  defibrinated  blood  was  then  mixed  with 
equal  parts  of  melted  neutral  or  faintly  alkaline  agar,  or  in  the  pro- 
portions of  2  parts  of  blood — or,  better,  3  parts — to  1  of  agar,  and 
allowed  to  soUdify  in  the  slanting  position,  after  which  the  conden- 
sation water  was  inoculated.  Great  care  had  to  be  taken  in  keeping 
the  constituents  of  the  medium  sterile  during  all  the  manipulations, 
as  the  sterilization  of  the  finished  product  was  Impracticable,  owing 
to  the  firm  coagulation  and  alteration  of  the  blood  by  the  heat. 


14  DOURINE   OF   HORSES:   ITS  CAUSE   AND   SUPPRESSION. 

Rouget  attempted  to  cultivate  the  Trypanosoma  equiperdum  at 
37°  C,  but  was  uniformly  unsuccessful,  the  organism  never  multiply- 
ing and  only  remaining  alive  for  24  hours.  The  same  results  attended 
all  our  early  efforts,  although  the  cultures  were  invariably  kept  at 
room  temperature.  The  organism,  however,  seemed  to  flourish  in 
white  rats,  and,  if  anything,  it  became  more  virulent  for  them  by 
successive  inoculations,  appearing  in  greater  and  greater  numbers  in 
the  blood  and  viscera  at  post-mortem  until  finally  hanging-drop 
preparations  made  from  the  blood  seemed  to  be  alive  with  the  minute 
wriggling  organisms.  One  loopful  of  this  blood  would  contain  prob- 
ably 200  or  even  more  of  these  trypanosomes.  The  continued 
inoculation  of  a  medium  composed  of  three  parts  of  blood  to  one  of 
agar  with  such  great  numbers  of  the  organism  was  finally  crowned 
with  success,  since  which  time  14  generations  have  been  grown,  cov- 
ering a  period  of  over  nine  months,  and  no  difficulty  was  experienced 
in  keeping  the  trypanosomes  alive  by  frequently  transferring  them 
to  fresh  medium.  The  cultures  were  finally  destroyed  through  con- 
tamination of  the  media.  The  inoculation  of  experiment  animals 
with  these  cultures  seems  to  indicate  that  there  was  some  reduction 
in  their  virulence,  but  too  small  a  number  of  inoculations  have  been 
made  to  draw  definite  conclusions. 

The  first  three  attempts  at  cultivating  this  protozoan  were  direct 
failures,  as  the  6  tubes  used  in  the  first  two  cases  and  9  in  the 
third  failed  to  show  any  trypanosomes  after  the  fourth  day.  The 
fourth  inoculation,  consisting  of  11  tubes  made  on  March  9  with 
blood  agar  (3  to  1)  resulted  in  the  multiplication  and  development  in 
one  tube  of  trypanosomes,  but  after  the  sixteenth  day  this  encourag- 
ing culture  died,  and  despite  subinoculations  no  further  growth  could 
be  obtained.  On  April  12  a  fifth  attempt  was  entirely  successful,  as 
3  of  the  14  tubes  inoculated  gave  evidence  of  development.  After 
the  inoculation  of  the  medium  with  the  infected  blood  the  tubes 
were  sealed  with  paraffin  or  sealing  wax  and  placed  in  a  dark  closet 
at  room  temperature.  Six  days  later  a  drop  of  the  water  of  conden- 
sation was  examined  and  found  to  contain  a  number  of  very  active 
trypanosomes,  some  that  were  languid,  showing  a  tendency  to  agglom- 
erate, and  also  many  degenerated  and  inactive  organisms.  On  each 
succeeding  day  the  number  of  the  latter  seemed  to  be  augmented, 
while  the  very  active  forms  were  rapidly  decreasing,  until  the  twelfth 
day,  when  the  tubes  showed  numerous  irregular  granular  bodies 
which  were  small,  contracted,  and  rounded,  representing  degenerated 
forms  of  the  trypanosome.  Two  days  later  small  forms,  about  one- 
half  the  size  of  the  adult  organism,  were  observed  gathered  together 
in  colonies  containing  from  4  or  5  to  20  or  30  individuals.  These 
were  actively  motile,  and  by  their  appearance  suggested  a  new 
generation  of  parasites.     The  smaller  colonies  were  in  several  cases 


CAUSE.  15 

attached  to  a  red  blood  corpuscle.  No  undulating  membrane  could 
be  detected  on  the  bodies  of  the  parasites,  and  it  was  very  difficult  to 
determine  whether  these  bodies  were  gathered  together  with  their 
anterior  or  posterior  extremity  directed  inward;  in  some  cases, how- 
ever, very  fine  filaments  could  be  seen  in  the  center  of  the  colonies 
or  rosettes. 

These  colonies  increase  in  number  and  size  until  one  clump,  by  the 
coalescence  of  numerous  smaller  groups,  may  contain  several  hun- 
dred closely  packed  wriggling  forms  of  trypanosomes.  The  elements 
in  these  united  clumps  are  arranged  radially  like  the  clusters  of 
actinomyces.  (See  PI.  I,  fig.  2.)  Such  large  colonies  are  not  fre- 
quent and  are  always  irregular,  and  usually  elongate  in  outline.  As 
they  grow  older  some  of  the  individuals  become  disengaged  and 
wriggle  around,  frequently  throwing  their  flagella  about  a  red  cell, 
and  move  about  in  a  circle,  but  with  less  activity  than  is  shown  by 
the  original  organisms.  The  flagella  appear  usually  longer  than  the 
length  of  the  trypanosome's  body.  At  times  individuals  are  seen 
united  in  pairs  by  their  posterior  extremities.  Many  involution 
forms  and  bodies  representing  developmental  stages  may  also  be 
observed  with  an  irregular  nucleus,  one  or  several  vacuoles  in  the 
posterior  extremity,  and  several  small  granular  bodies  at  the  anterior 
extremity.  These  organisms  are  of  various  shapes,  from  long,  narrow, 
crescentic  forms  to  short,  thick  bodies  hke  tadpoles.  Some  of  these 
organisms  are  inactive  and  are  probably  involution  or  transitional 
forms,  while  others  are  quite  motile  and  represent  the  developmental 
stages.  The  nuclei  of  the  former  seem  to  be  the  first  to  alter  their 
shape,  assuming  various  peculiar  positions  and  finally  disappearing. 
The  cell  body  then  contains  a  number  of  small  vacuoles  scattered 
irregularly  throughout  its  protoplasm.  The  protoplasm  finally  con- 
tracts into  a  spherical  body  or  may  disappear  entirely,  leaving  the 
centrosome  attached  to  the  flagella  and  giving  the  appearance  of  a 
spermatozoan. 

The  growth  of  these  protozoa  in  the  blood-agar  medium  gave  but 
slight  microscopic  evidence  of  development.  No  colonies  appeared 
on  the  slanted  surface  of  the  medium,  and  the  only  indications 
denoting  growth  were  a  slightly  increased  turbidity  of  the  water  of 
condensation  and  a  flocculent  precipitate  at  the  bottom  which  con- 
tained many  bodies. 

SEARCHING  FOR  THE  TRYPANOSOMES. 

After  the  trypanosome  had  been  obtained  and  studied  a  mare 
and  a  Percheron  stalUon  affected  with  the  American  form  of  the 
disease  were  shipped  to  Washington  from  the  West  in  1904.  These 
animals,  particularly  the  stalhon,  exhibited  all  the  characteristic 
symptoms  of  the  disease  and  were  considered  typical  cases  in  which 


16  DOURINE  OF   HORSES:   ITS  CAUSE  AND   SUPPRESSION. 

to  find  the  trypanosomes.  Blood  was  drawn  from  the  animals  two 
and  three  times  weekly  from  both  the  veins  and  from  plaques  or 
urticarial  swellings  which  appeared  frequently  on  the  stallion.  On 
several  occasions  blood  was  drawn  at  midnight  in  order  to  insure 
the  detection  of  the  parasites  in  case  they  were  only  present  in  the 
circulation  nocturnally.  Without  exception,  however,  no  trypa- 
nosomes were  found,  and  post-mortem  examinations  held  on  these 
animals  were  negative  for  these  parasites  in  every  case.  Further, 
numerous  experimental  animals,  including  rabbits,  guinea  pigs,  rats, 
mice,  and  dogs,  were  inoculated  with  small  quantities  of  blood  and 
various  other  fluids  from  the  diseased  horses,  with  negative  results 
and  although  in  some  cases  death  of  the  small  experimental  animals 
seemed  to  result  from  inoculation  after  a  progressive  emaciation 
lasting  over  a  period  of  three  to  five  months,  the  majority  of  these 
animals  died  of  some  intercurrent  disease  without  showing  any 
trypanosomes.  From  the  fact  that  the  trypanosome  was  found 
rather  easily  in  the  animals  dead  of  the  European  disease,  with  the 
exception  of  rabbits,  and  that  the  most  careful  examination,  micro- 
scopical as  well  as  inoculation  tests  failed  to  show  the  parasite  in 
the  natural  disease  of  this  country  until  the  1911  outbreak  of  dourine 
in  Iowa,  it  seems  conclusive  to  the  writer  that  the  Trypanosoma 
equiperdum  are  fewer  in  number,  less  aggressive,  and  not  as  virulent 
in  the  dourine  of  the  United  States  as  they  are  in  the  countries  where 
the  disease  is  indigenous.  In  fact,  the  disease  appears  to  be  more 
acute  and  fatal  in  Asia  and  northern  Africa  than  in  Europe,  and  the 
Trypanosoma  equiperdum  at  the  same  time  are  more  easily  detected, 
wliile  in  America  the  disease  is  even  less  acute  and  fatal  than  in 
Europe  and  the  trypanosome  even  more  elusive. 

The  technique  used  in  finding  the  trypanosomes  in  the  recent  Iowa 
outbreak  was  to  select  a  freshly  formed  plaque,  from  which  the  hair 
was  shaved  and  the  skin  disinfected  with  carboHc  acid  followed  by 
alcohol  and  distilled  water.  The  skin  over  the  plaque  was  next 
scarified  with  a  sharp  scalpel,  as  in  human  vaccination,  until  the 
serum  commenced  to  ooze  from  the  capillaries.  A  water-vacuum 
apparatus  was  then  prepared  in  order  to  aspirate  the  serum  from 
the  plaque.  An  ordinary  strong  wash  bottle  was  obtained,  in  the 
neck  of  which  was  placed  a  rubber  cork  with  two  openings  contain- 
ing a  short  and  a  long  glass  tube.  The  long  tube  was  connected  by 
rubber  tubing  to  a  funnel,  which  was  held  against  the  plaque,  while 
the  short  tube  was  connected  with  a  water-exhaust  pump.  A  small 
cotton  plug  was  left  in  the  short  tube  of  the  wash  bottle  to  prevent 
the  return  of  unfiltered  air  when  the  exhaust  apparatus  was  removed. 
The  water  was  then  turned  on  and  the  aspirating  faucet  slowly  set 
to  work  in  order  that  the  exhaust  would  not  be  too  great  at  the  begin- 
ning.    By  this  method  the  blood-tinged  serum  was  readily  drawn 


INFECTIVENESS.  17 

into  the  bottle  and  about  10  c.  c.  collected.  This  was  subsequently 
centrifugalized  and  the  upper  layer  of  sediment  examined  in  fresh 
smear  preparations,  with  the  result  that  trypanosomes  were  observed 
in  limited  numbers.  They  have  always  been  very  scanty  and  are 
only  found  after  prolonged  and  tedious  examination.  Horse-meat 
bouillon,  rabbits,  and  rats  have  been  inoculated  with  the  lower 
strata  of  tliis  fluid,  but  thus  far  only  the  latter  have  revealed  the 
presence  of  these  protozoa. 

INFECTIVENESS. 

Material  taken  directly  from  infected  horses  seems  to  possess  a  very 
fluctuating  virulence  for  small  experimental  animals.  While  in  Alge- 
ria rabbits  and  dogs,  as  well  as  mice  and  rats,  could  be  successfully 
infected,  in  Hungary  the  material  from  horses  affected  with  dourine 
has  only  proved  to  be  virulent  for  sohpeds.  Thus,  as  Marek  has 
already  pointed  out,  it  seems  that  the  virus  has  much  more  viru- 
lence in  the  southern  than  in  the  northern  countries,  or  that  it 
requires  the  injection  of  a  large  amount  of  fluid,  wliich  small  experi- 
ment animals,  as  a  rule,  do  not  receive,  in  order  to  include  a  sufficient 
number  of  trypanosomes  to  produce  the  disease. 

The  fact  that  under  natural  conditions  dourine  is  transmitted 
solely  by  coition  causes  it  to  differ  from  all  other  trypanosomiases, 
since  the  latter,  so  far  as  is  known,  are  propagated  by  a  biting  insect, 
usually  a  fly,  acting  as  a  vector  or  carrier.  Thus  the  trypanosome 
of  dourine  has  the  abihty  to  penetrate  the  intact  mucosa  of  the  geni- 
tal tract,  whereby  it  reaches  the  blood,  and,  later,  the  more  distant 
parts  of  the  body.  It  takes  its  nourishment  by  osmosis  and  does  not 
invade  the  blood  cells.  Its  pathogenic  action  seems  to  result  from 
the  production  of  certain  not  yet  determined  poisons,  which  act  first 
on  the  peripheral  nerves  and  later  on  the  general  nervous  system. 
A  cellular  infiltration  of  the  nerve  tissues  develops,  wherefrom  the 
nerve  fibers  as  well  as  the  nerve  cells  degenerate  and  finally  com- 
pletely disappear. 

Some  authors  are  of  the  opinion  that  the  disease  has  a  more  rapid 
and  unfavorable  course  in  stalhons  than  in  mares,  while  in  asses  the 
disease  in  most  cases  is  confined  to  the  local  infection  of  the  genital 
organs.  Although  the  predisposition  of  solipeds  to  the  infection  is 
quite  marked,  not  all  stallions  which  serve  diseased  mares  or  all 
mares  served  by  infected  stallions  contract  the  disease.  According 
to  Roll,  about  66  per  cent  of  the  mares  exposed  to  the  infection 
become  diseased. 

A  striking  illustration  of  how  a  stallion  may  transmit  the  disease 
from  an  infected  to  a  healthy  mare  without  contracting  the  disease 
himself  is  given  in  the  case  of  stallion  31.  Frequent  attempts  were 
834°— Bull.  142—11 3 


18  DOURINE   OF   HORSES:   ITS   CAUSE   AND   SUPPRESSION. 

made  to  infect  this  horse  through  service  with  mare  30,  affected  with 
dourine,  but  without  results.  Finally,  on  June  4,  1902,  the  horse 
was  allowed  to  serve  a  native  Virginia  mare  (No.  32)  shortly  after 
coition  with  mare  30.  This  was  repeated  during  the  next  five  days. 
On  June  20  the  mucosa  of  the  vulva  of  mare  32  was  erythematous, 
and  rabbits  and  guinea  pigs  were  inoculated  with  the  secretion  with- 
out results.  On  June  29,  when  the  mare  was  taken  out  of  the  stable 
for  another  service,  her  gait  was  noticed  to  be  unsteady  behind. 
She  seemed  to  have  a  rolling  motion  from  side  to  side,  and  it  was 
thought  that  she  would  not  have  sufficient  strength  to  support  the 
male  on  her  back.  During  the  next  few  days  she  seemed  nervous 
and  to  be  falling  off  in  flesh,  although  her  appetite  remained  good. 
On  July  5  the  mare  became  acutely  ill  about  4  a.  m.  At  9  a.  m. 
she  went  down  on  her  side  with  head  thrown  back  and  back  curved 
downward.  She  was  completely  paralyzed,  being  unable  to  regain 
her  feet  even  with  assistance.  Her  respiration  was  quite  rapid,  both 
abdominal  and  thoracic.  Her  abdomen  was  somewhat  distended 
with  gas  and  she  passed  a  little  gas  constantly.  Her  eyes  had  a 
sunken  appearance,  but  there  was  no  perspiration  apparent.  There 
was  a  slight  discharge  from  the  vulva,  the  mucosa  of  which  was 
extremely  inflamed.  The  mare  died  at  6  p.  m.,  and  an  autopsy  was 
made  the  following  morning. 

The  autopsy  showed  the  heart  to  be  normal,  lungs  congested,  liver 
pale,  yellow,  and  friable,  kidneys  slightly  pale,  spleen  normal  in  size, 
w^ith  a  few  ecchymoses  under  the  capsule.  The  posterior  portion  of 
the  diaphragm  was  covered  with  fine  white  bands  of  fibrous  tissue. 
The  intestines  were  filled  with  gas,  but  otherwise  empty.  Small  dif- 
fused extravasations  of  blood  were  noted  under  the  serous  membrane 
of  the  cecum  and  the  large  colon.  The  right  ovary  was  enlarged,  and 
softened  with  cysts.  The  left  ovary  appeared  normal  in  size,  but 
contained  small  cysts.  The  mucous  membrane  of  the  uterus  was 
edematous  and  hemorrhagic  in  patches.  The  os  was  inflamed  and 
the  vagina  contained  edematous  and  hemorrhagic  areas.  The 
vulva  was  inflamed  and  contained  one  mucoid  cyst  and  numerous 
petechial  hemorrhages.  The  bladder  showed  cystitis  and  was  lined 
with  a  yellowish  exudate. 

What  effect  the  complicating  attack  of  flatulent  colic  had  upon  the 
course  of  the  disease  is  difficult  to  determine,  but  it  is  the  only  case 
in  our  experience  of  such  short  duration  and  with  such  acute  lesions 
of  the  genitals.  Inoculations  of  material  from  this  mare  into  rabbits, 
guinea  pigs,  rats,  and  a  dog  were  attended  with  negative  results. 

In  order  to  compare  the  results  obtained  from  the  inoculation  of 
material  from  a  case  of  natural  dourine  with  the  disease  produced 
by  the  injection  of  virulent  material  from  France,  the  following  exper- 
imental cases  in  equines  are  appended.     These  cases  have  brought 


BuL.  142,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  II. 


Fig.  1.— Percheron  Stallion  42,  Showing  Condition  at  the  Time  of  Purchase. 


Fig.  2.— Same  Stallion  After  Dourine  had  Developed. 
Spots  on  side  and  croup  give  location  of  plaques. 


BuL.  142,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  III. 


Fig.  1.— Percheron  Mare  80,  Showing  Chronic  Dourine. 

Observe  the  "tucked  up"  abdomen  and  emaciation  having  lost  over  700  pounds  in  the  previous 

four  months. 


Fig.  2.— Mare  47  in  the  Last  Stage  of  Dourine. 

Notice  the  position  of  the  off  liiiid  foi)t  and  the  straightened  liock  joints. 


INFECTIVENESS.  19 

forward  some  interesting  facts  about  the  transmission  of  the  disease, 
and  may  be  divided  into  two  series : 

1.  A  case  in  which  the  American  disease  was  transmitted  by  a 
stallion  indirectly  from  an  infected  to  a  normal  mare,  which  has  been, 
described  above  under  the  notes  on  mare  32. 

2.  Cases  in  which  both  the  American  and  the  European  disease 
were  transmitted  by  subcutaneous  inoculations  of  infected  blood. 

In  conducting  the  latter  experiments  a  female  ass  was  injected 
with  serum  taken  from  plaques  which  appeared  intermittently  on 
stallion  42.  Before  describing  the  results  of  these  injections  brief 
notes  will  be  given  of  the  symptoms  and  lesions  manifested  in  this 
stallion. 

Stallion  No.  42. 

• 

Black  stallion  received  April  25,  1904,  showing  chronic  symptoms  of  dourine. 
This  case  was  one  of  the  most  typical  that  had  come  under  our  observation,  and  one 
of  the  few  cases  in  which  cutaneous  plaques  had  been  noted  up  to  that  time.  His 
condition  was  very  poor  and  showed  considerable  loss  of  coordination  in  the  hind 
quarters.  Several  deep  scars  were  noted  on  the  penis,  and  the  testicles  were  swollen. 
Plates  II  and  III  will  give  a  good  idea  of  his  appearance  before  and  after  showing 
symptoms  of  dourine. 

April  26.  Stallion  served  mare  43  after  she  had  been  served  by  stallion  31. 

May  2.  Stallion  served  mare  43.     A  new  plaque  has  appeared  on  left  shoulder. 

May  11.  The  plaque  developing  on  left  shoulder  is  now  well  developed,  about  3 
inches  in  diameter  by  one-eighth  to  one-foiu-th  inch  in  height,  and  has  a  well-defined 
border. 

An  incision  was  made  into  plaque  and  blood  drawn  to  inject  rats  and  rabbits.  Fre- 
quent inoculations  of  small  animals  were  made  with  the  contents  of  the  plaques,  but 
always  with  negative  results. 

May  12.  The  plaque  noted  yesterday  seems  to  be  slightly  decreased.  A  new  one 
about  IJ^  inches  in  diameter  is  forming  back  of  right  shoulder. 

May  13.  Stallion  is  losing  in  condition  and  is  very  hollow  in  flanks.  The  plaque 
on  left  shoulder  is  still  present  but  is  reduced  in  height.  Three  plaques  are  present  on 
back  of  right  shoulder.  •  One  plaque  is  forming  in  front  of  right  shoulder. 

May  14.  The  plaques  are  disappearing. 

May  17.  Stallion  served  mare  43  and  then  mare  36. 

May  19.  Has  two  small  plaques  on  right  side  and  one  on  left  shoulder.  The  one 
in  front  of  right  shoulder  is  disappearing. 

May  20.  Served  mares  43  and  36  in  the  same  manner  as  on  May  17.  Has  two  small 
plaques  back  of  left  shoulder  and  two  small  ones  on  right  side.  The  one  in  front  of 
right  shoulder  from  which  blood  was  drawn  has  disappeared. 

May  21.  Has  five  small  plaques  on  right  side,  one  back  of  right  shoulder,  one  back 
of  and  one  on  left  shoulder;  the  latter  is  very  small. 

May  23.  Has  two  plaques,  one  about  3^  inches  in  diameter,  and  the  other  about  2 
inches  in  diameter,  back  of  left  shoulder,  and  one  plaque  about  3  inches  in  diameter 
on  right  side. 

May  24.  Has  one  plaque  about  4  by  5  inches  in  diameter  on  left  shoulder  and  one 
about  6  inches  in  diameter  just  in  front  of  left  flank. 

May  26.  Plaques  have  nearly  disappeared.  Animal  is  extremely  thin.  An 
attempt  was  made  yesterday  to  have  him  serve  mare  41,  but  he  was  unable  to  have  an 
erection. 


20  DOUBINE  OF   HORSES:   ITS  CAUSE  AND   SUPPRESSION. 

May  27.  The  plaques  have  about  disappeared. 

May  28.  No  plaque.^  visible.  Hind  legs  from  hocks  down  are  swollen.  An  attempt 
was  again  made  to  have  him  serve  mare  41,  but  he  was  unable. 

May  31.  Has  two  small  plaques  on  left  hip.  The  hocks  and  below  hocks  are  much 
swollen. 

June  1.  Stallion  served  healthy  mare  41  to-day. 

June  2.  Has  one  plaque  4  inches  in  diameter  on  left  hip,  and  one  about  3  by  4 
inches  in  diameter  on  right  side.     Legs  from  hocks  down  are  still  swollen. 

June  3.  Plaques  same  as  yesterday,  and  hocks  are  much  swollen. 

June  4.  The  plaques  are  disappearing. 

June  6.  The  two  plaques  not«d  on  left  hip  several  days  ago  have  not  yet  entirely 
disappeared.     No  now  ones  present. 

June  9.  Plaque  on  left  hip  from  which  blood  was  last  drawn  is  still  present.  The 
new  one  near  root  of  tall  has  almost  disappeared.     No  new  ones. 

June  10.  Has  two  small  plaques  on  back  to  the  right  of  the  spinal  column. 

June  11.  The  plaque  from  which  blood  was  last  drawn  has  disappeared.  The  two 
plaques 'noted  yesterday  are  still  present. 

June  15.  The  two  plaques  noted  on  side  are  slowly  increasing  in  size  and  height. 
A  new  one  is  beginning  to  develop  on  opposite  side. 

June  17.  Plaques  still  present.     Swollen  condition  of  hocks  has  disappeared. 

June  18.  Has  one  plaque  2  by  4  inches  in  size  on  right  flank,  one  about  2  inches  in 
diameter  on  back  to  the  right  of  spinal  column,  and  one  on  left  side. 

June  20.  Plaques  same  as  noted  yesterday,  except  that  a  new  one  about  IJ  inches 
in  diameter  has  formed  on  left  shoulder. 

June  22.  The  plaque  on  left  shoulder  is  a  little  larger  than  on  yesterday.  One 
still  present  on  left  side.     None  present  on  right  side. 

June  24.  Has  three  plaques  on  left  side  of  back.     Sheath  somewhat  swollen. 

June  28.  Has  an  edematous  area  4  by  8  by  2  inches  in  size  on  chest  to  left  of  ster- 
num. One  plaque  2  inches  in  diameter  in  left  axilla,  one  the  same  size  in  front  of 
left  shoulder  (the  hair  has  been  rubbed  from  the  surface  of  this  one),  one  1^  inches 
in  diameter  on  left  flank,  one  about  5  inches  in  diameter  on  left  hip,  and  two  small 
ones  back  of  right  shoulder. 

June  29.  Seems  about  the  same  as  yesterday.  An  attempt  was  made  to  have  this 
stallion  serve  mare  43,  but  while  he  had  no  trouble  to  have  an  erection  he  made  no 
attempt  to  mount  the  mare,  though  she  seemed  very  anxious  to  have  him  do  so. 

July  2.  Has  had  a  raw  sore  1|  inches  in  diameter  on  right  flank,  which  looks  as 
though  it  might  have  been  caused  by  rubbing.  Has  two  small  plaques  on  the  chest 
to  left  of  sternum.  No  other  plaques  visible.  Appetite  is  good  and  he  is  in  about 
the  same  condition  as  for  some  time  past. 

July  6.  Has  one  plaque  about  4  inches  in  diameter  on  left  hip;  three  very  low 
ones,  each  about  1^  inches  in  diameter,  in  front  of  left  shoulder;  one  about  3  inches 
in  diameter  back  of  right  shoulder.     Animal  seems  to  be  holding  his  own. 

July  11.  Has  one  plaque  about  4^  inches  in  diameter  back  of  left  shoulder  and 
one  about  2^  inches  in  diameter  on  left  hip.  The  sore  on  right  flank,  noted  some 
time  ago,  does  not  heal  and  now  has  an  unhealthy  appearance. 

July  16.  No  plaques  visible.  Sore  on  right  flank  healing.  Condition  of  animal 
is  poor,  but  he  seems  to  be  holding  his  own. 

July  23.  Losing  in  condition.  Has  one  plaque  about  2^  inches  in  diameter  on 
left  hip. 

July  27.  Has  a  plaque  about  3  by  4  inches  in  diameter  on  right  hip  at  root  of  tail; 
this  was  noticed  for  the  first  time  yesterday  afternoon.  The  one  noted  on  left  hip 
some  time  ago  is  still  present  and  is  about  4  inches  in  diameter. 

August  3.  Plaque  on  left  hip  still  present;  shape  and  size  changes  from  day  to 
day.    The  one  on  right  hip  from  which  blood  was  drawn  has  disappeared. 


INFECTIVENESS.  21 

August  9.  Plaque  on  left  hip  still  present.  No  new  ones.  Condition  of  animal  is 
very  poor,  but  he  has  a  good  appetite  and  is  bright. 

September  10.  One  plaque  has  appeared  on  left  lumbar  region. 

September  20.  Donkey  34  injected  subcutaneously  in  left  side  of  neck  with  10  c.  c. 
of  blood  drawn  from  a  plaque  on  left  hip. 

(Note. — This  donkey  is  to  be  injected  whenever  suitable  plaques  appear  on 
stallion.) 

Stallion  has  three  plaques  on  each  hip,  each  in  size  from  2  to  3  inches. 

September  30.  Hind  legs  much  swollen,  also  scrotum  and  sheath.  Several  plaques 
on  thighs. 

October  3.  Plaques  have  almost  disappeared.     General  condition  very  poor. 

October  5.  Has  been  down  since  yesterday  morning,  and  is  helpless.  Respiration 
"very  much  accelerated . 

Forty  cubic  centimeters  of  blood  drawn  and  used  to  inject  donkey  34. 

October  6.  Still  lies  stretched  out,  and  respiration  is  quite  rapid. 

October  7.  Found  dead  this  morning. 

The  temperature  of  this  animal  taken  twice  daily  since  April  26  shows  a  range 
between  101°  and  102.8°  F.  Many  microscopic  examinations  of  the  contents  of  the 
plaques  failed  to  reveal  any  trypanosomes. 

The  post-mortem  examination  showed  that  the  carcass  was  very 
emaciated  and  anemic,  and  would  probably  weigh  not  more  than 
1,100  pounds.  Several  small  bed  sores  were  observed,  involving  the 
skin  and  underlying  tissues  in  the  region  of  the  pelvic  prominences 
and  the  elbow  joint.  On  skinning,  the  hide  seemed  dry  and  tough, 
and  in  the  region  of  the  gluteal  muscles  of  the  right  side  three  yellow- 
ish gelatinous  areas  with  injected  blood  vessels  were  seen,  about  the 
size  of  a  quarter,  which  represented  the  location  of  the  last  observed 
plaques.  On  the  dependent  (left)  side  of  the  carcass  the  subcutaneous 
tissues  were  infiltrated  with  a  thick  layer  of  coagulated  serum  that 
had  exuded  from  the  blood  vessels.  The  great  dorsal  muscles  on 
both  sides  of  the  spine  in  the  lumbar  region  were  softened,  swollen, 
and  contained  numerous  small  hemorrhagic  areas.  On  opening  the 
thoracic  cavity  both  lungs  were  found  to  be  edematous,  while  the 
left  was  also  engorged  with  blood  as  a  result  of  hypostatic  congestion. 
The  heart  was  normal  and  contained  black,  feebly  coagulated  blood. 
The  hver  appeared  normal  with  the  exception  of  several  small 
yellowish  areas  of  necrosis,  probably  of  parasitic  origin.  The  spleen 
was  sUghtly  shrunken  and  showed  numerous  pin-point  hemorrhages 
under  the  capsule.  The  right  kidney  was  apparently  without  lesions, 
while  the  left  organ  was  hypostatically  injected.  The  stomach 
contained  a  small  number  of  bots,  while  the  large  intestine  showed 
several  small  hemorrhagic  points,  the  result  of  the  40  or  50  scleros- 
tomes  which  it  harbored.  The  spinal  cord  in  the  lumbar  region 
contained  many  petechial  hemorrhages,  while  the  meninges  were 
slightly  inflamed.  There  was  also  an  excess  of  serous  fluid  in  the 
spinal  canal.  The  penis  showed  many  depigmented  areas  of  irregular 
shapes  and  sizes,  but  at  least  two  of  these  patches  were  raised,  hard, 
and  dense,  resembling  cicatricial  tissue.     The  urethra  was  normal. 


22  DOUBINE  OF   HORSES:   ITS  CAUSE   AND   SUPPRESSION. 

The  testicles  were  atrophied  somewhat  and  sHghtly  denser  in  con- 
sistency than  normal.  The  tunica  vaginalis  of  both  testicles  showed 
17  hemorrhagic  patches  of  projecting  villi  and  2  or  3  warty  neoplasms 
were  present  on  the  tunica  propria.  At  the  apex  of  the  testicular  sac 
on  the  right  side  a  large  diffused  hemorrhagic  patch  was  observed, 
with  several  fibrous  bands  adhering  to  the  testicle.  This  sac  also 
contained  an  excess  of  yellowish  transparent  fluid  exudate. 

It  is  interesting  to  note  in  connection  with  this  case  that  although. 
neither  of  the  healthy  mares  which  were  served  by  this  stallion  con- 
tracted dourine,  and  the  injection  of  numerous  dogs,  rats,  rabbits,  and 
guinea  pigs  resulted  negatively,  nevertheless  serum  taken  from  the 
plaques  and  blood  from  the  jugular  when  injected  subcutaneously  into 
donkey  34  produced  the  disease,  but  did  not  show  any  trypanosomes. 
The  notes  on  this  donkey  follow. 

Donkey  No.  34. 

September  20,  1904.  Injected  subcutaneously  in  left  side  of  neck  with  10  c.  c.  of 
blood  drawn  from  a  plaque  on  left  hip  of  stallion  42. 

October  5.  Injected  subcutaneously  in  front  of  left  shoulder  with  60  c.  c.  of  whole 
blood  drawn  to-day  from  jugular  of  stallion  42. 

October  7.  A  firm  swelling  10  inches  in  diameter  by  3  inches  high  is  noticed  at 
seat  of  injection. 

October  18.  No  abscess  has  formed  at  seat  of  injection,  but  there  is  still  present  a 
very  firm  enlargement  about  3  by  3  by  1  inches  in  size. 

November  19.  Vulva  somewhat  swollen.  Mucosa  of  vagina  reddened.  Animal 
has  a  patch  of  edema  about  6  inches  in  diameter  by  1  inch  high  on  abdomen.  The 
skin  over  an  area  4  inches  in  diameter  at  seat  of  injection  is  indurated.  These  symp- 
toms were  first  observed  November  16. 

November  28.  Vulva  still  swollen;  vagina  congested.  Edema  on  abdomen  has 
almost  disappeared.  A  hard  spherical  nodule  about  1\  inches  in  diameter  is  seen 
about  6  inches  below  seat  of  injection.  This  is  firmly  adherent  to  the  deeper  struc- 
tures but  not  to  the  skin. 

December  2.  Swelling  of  vulva  is  increasing  slowly. 

December  6.  Vulva  still  swollen  and  vagina  congested.  Many  small  eruptions 
on  shoulders  and  withers,  which  cause  the  hair  to  fall  out  in  patches. 

December  10.  A  patch  of  edema  about  6  by  14  by  1  inches  in  size  over  sternum 
and  abdomen;  loose  tissue  in  left  flank  edematous,  and  left  inguinal  lymph  gland 
somewhat  enlarged.  Vulva  is  still  swollen.  The  eruptions  on  sternum  same  as  on 
withers.     Nodule  in  front  of  left  shoulder  same  as  last  noted . 

December  12.  Edema  on  flank  is  slightly  reduced;  that  on  abdomen  same  as  last 
noted.  Vulva  still  swollen.  Mammse  slightly  edematous.  Eruptions  on  skin  still 
present. 

December  20.  Vulva  much  swollen.     Eruptions  on  skin  increasing. 

December  29.  Animal  has  a  large  patch  of  edema  about  1  inch  in  height  extending 
over  ventral  aspect  of  body.    Vulva  still  swollen. 

January  7,  1905.  Edema  over  ventral  aspect  of  body.  Vulva  much  swollen. 
Area  of  edema  in  left  flank. 

January  10.  Vulva  very  much  swollen,  also  hips  for  a  distance  of  5  or  6  inches 
to  either  side.  Nodule  in  front  of  shoulder  is  still  present.  Only  a  small  amount  of 
edema  on  aspect  of  body  or  in  left  flank. 


INFECTIVENESS.  23 

January  11.  About  350  c.  c.  blood  drawn  from  right  jugular;  60  c.  c.  of  this  was 
injected  immediately  into  left  jugular  of  donkey  37;  the  balance  was  defibrinated, 
and  60  c.  c.  injected  intravenously  into  donkey  43.  (See  records  of  donkeys  37  and 
43.) 

January  12.  Swelling  of  vulva  and  hip  not  nearly  so  great  as  it  was  yesterday. 
No  edema  over  ventral  aspect  of  body.  Many  eruptions  still  present  on  shoulders 
and  back.    Appetite  not  as  good  as  usual. 

January  13.  Vulva  swollen  about  the  same.  Hips  for  a  distance  of  5  or  6  inches 
around  vulva  much  swollen.    Appetite  better. 

January  16.  Swelling  of  vulva  slightly  reduced;  that  of  hips  has  increased  slightly. 

January  20.  Swelling  of  vulva  increased  a  little  over  what  it  had  been  for  the  past 
few  days.  No  change  in  swelling  of  hips.  A  hard  nodule  about  3  cm.  in  diameter  has 
appeared  at  point  about  5  cm.  to  left  of  anus. 

January  23.  Swelling  of  vulva  increased. 

January  31.  Animal  has  an  enlargement  about  3  inches  in  diameter  by  2  inches 
in  height  immediately  to  left  of  anus.  This  enlargement  has  a  hard  sensitive  border 
and  a  soft  center  about  1  inch  in  diameter.  The  vulva  is  still  swollen  and  edema  is 
fltill  present  on  rear  of  thighs  and  in  left  flank.  Nodule  in  front  of  left  shoulder  still 
present. 

February  1.  Abscess  which  has  formed  at  side  of  anus  is  broken  and  is  discharging 
sero-purulent  fluid. 

February  2.  Abscess  has  discharged  all  of  its  contents.  Swelling  and  skin  lesions 
are  about  same  as  last  noted. 

February  11.  Has  a  patch  of  edema  about  4  by  5  by  1  inch  between  forelegs. 
Vulva  and  tissues  surrounding  it  much  swollen.     Abscess  completely  healed. 

February  17.  Vulva  and  rear  of  thighs  much  swollen.  Considerable  edema  over 
abdomen  and  between  forelegs.  Many  small  eruptions  over  neck  and  shoulders. 
The  hair  in  this  region  has  fallen  out. 

February  20.  Same  as  last  noted,  and  in  addition  a  plaque  2  by  3  inches  in  area  on 
left  side  of  neck. 

February  2 1 .  About  same  as  yesterday . 

February  23.  Skin  disease  lesions  still  present  and  spreading.  Enlargement  in 
front  of  left  shoulder  increasing  in  size.  Edema  still  present  between  forelegs  and 
abdomen.     Vulva  still  swollen. 

March  8.  Portion  of  hips  still  swollen.  Vulva  and  loose  tissue  below  it  are  swollen. 
Enlargement  in  front  of  left  shoulder  increasing  in  size.  Small  enlargement  at  seat 
of  blood  injection. 

March  17.  Edema  between  forelegs  and  over  abdomen.  Vulva  and  loose  tissue 
between  it  and  udder  edematous.  Enlargement  in  front  of  left  shoulder  same  as  last 
noted. 

April  1.  Udder  and  vulva  swollen. 

April  10.  Same  as  last  noted. 

May  5.  Vulva  and  udder  still  swollen. 

May  16.  Vulva  slightly  swollen.  Swollen  area  one-half  to  IJ  inches  high  and  16 
inches  in  diameter  surrounding  anus  and  vulva.     Both  prescapular  glands  enlarged. 

May  25.  Prescapular  glands  still  enlarged.  Edema  in  inguinal  region.  Vulva  and 
hips  swollen. 

May  29.  Hips  and  vulva  slightly  swollen.     No  plaques  visible. 

June  15.  Animal  seems  to  be  recovering.     Highest  temperature  noted,  102.4°  F. 

July  15.  Apparently  well. 

August  15.  Apparently  well. 

September  18.  Gave  birth  to  a  normal  male  colt. 

October  10.  Served  by  male  donkey  48  to-day,  and  on  four  previous  occasions, 
"without  infecting  the  male. 

May  18.  Killed  to-day.    All  organs  normal. 


f^0(5 


24  DOURiNE  OF  horses:  its  cause  and  suppression. 

As  already  mentioned,  the  blood  of  donkey  34  was  injected  into 
donkeys  37  and  43  on  January  11,  1905,  the  first  receiving  the  whole 
blood,  while  the  latter  received  the  filtrate.  The  records  of  these 
donkeys  which  follow  show  that  the  virus  was  successfully  held  back 
by  the  Chamberland  filter. 

Donkey  No.  43. 

January  11, 1905.  Injected  intx)  right  jugular  with  60  c.  c.  of  filtered  blood  of  donkey 
34.  This  blood  was  drawn  at  10  a.  m.  to-day,  was  defibrinated,  diluted,  filtered,  and 
injected  at  4.30  p.  m. 

Animal  is  now  in  fairly  good  condition  and  seems  to  be  well  in  every  respect. 

May  29.  Up  to  this  date  has  shown  no  symptoms,  and  temperature  has  not  exceeded 
100.4°  F. 

December  9.  Served  by  donkey  48  (by  mistake). 

December  26.  Female  foal  born  to-day. 

January  11,  1906.  Foal  and  dam  killed.     No  lesions. 

Donkey  No.  37. 

January  11,  1905.  Injected  into  right  jugular  with  60  c.  c.  of  whole  blood  of  don- 
key 34. 

January  23.  No  symptoms  of  disease. 

January  25.  Animal  has  a  plaque  about  3  inches  in  diameter  by  |  inch  in  height 
on  left  hip  a  short  distance  from  root  of  tail. 

January  28.  Plaque  on  hip  still  present.     No  other  lesions. 

February  11.  Plaque  has  almost  disappeared. 

February  17.  The  plaque  on  rear  of  left  hip  is  now  about  5  inches  in  diameter  by 
1  inch  high. 

February  21.  Superior  portion  of  neck  is  much  swollen.  Patch  of  edema  between 
forelegs.     Edema  on  thigh  still  present. 

February  23.  Skin  eruptions  of  shoulders;  hair  beginning  to  fall  out;  enlargement 
about  3  cm.  in  diameter  on  front  of  left  shoulder,  and  a  patch  of  edema  between  forelegs. 

February  24.  Vulva  swollen,  in  addition  to  symptoms  noted  yesterday. 

March  2.  An  enlargement  about  4  cm.  in  diameter  is  noted  at  right  of  vulva. 

March  8.  Animal  has  eruption  on  neck,  and  vulva  swollen  a  little. 

March  17.  Swelling  of  vulva  has  nearly  subsided.     Legs  in  region  of  hock  swollen. 

March  23.  Large  patch  of  edema  1  to  li  inches  in  height  extending  over  sternum  and 
abdomen.     Vulva  only  slightly  swollen. 

April  1.  Vulva  swollen  somewhat.  Edema  still  present  on  abdomen  but  reduced  in 
height.     Left  prescapular  gland  is  enlarged. 

April  4.  Vulva  swollen.     No  edema  on  abdomen. 

April  15.  Same  as  last  noted. 

April  20.  Vulva  much  swollen.  Mucous  membrane  in  region  of  os  uteri  is  edema- 
tous. 

May  5.  Large  patch  of  edema  on  chest  and  abdomen.  Vulva  swollen,  also  the 
tissue  between  it  and  the  udder. 

May  8.  Vulva  swollen,  an  edematous  ridge  1  i  inches  wide  by  IJ  inches  high  extend- 
ing from  vulva  to  a  point  on  left  side  of  udder  where  it  broadens  out  into  a  patch  3  by  4 
inches  in  area.  Large  patch  of  edema  on  abdomen;  small  abscess  formed  and  broken 
over  posterior  surface  of  knee;  left  front  leg  swollen,  and  a  shallow  ulcer  on  anterior 
surface  of  hock. 

May  9.  Right  foreleg  swollen,  pits  on  pressure,  discharging  abscess  at  posterior 
portion  of  knee  joint.  Vulva  much  swollen;  its  mucous  membrane  presents  a  some- 
what granular  appearance;  swollen  ridge  noted  yesterday  is  still  present. 


INFECTIVENESS.  25 

May  10.  Has  a  slight  vaginal  discharge;  has  a  plaque  about  4  by  3  inches  by  J  inch 
immediately  in  front  of  left  flank. 

May  11.  Plaque  noted  yesterday  is  still  present,  and  one  about  3  inches  in  diameter 
by  one-half  inch  high  is  present  a  short  distance  above  and  in  front  of  it.  A  third  one 
about  2  inches  in  diameter  by  \  inch  high  on  left  hip.  Swelling  on  left  front  leg  is 
subsiding.     Abscess  on  knee  is  still  discharging. 

May  12.  Plaques  about  same  as  noted  yesterday. 

May  17.  Abscess  on  left  knee  is  still  discharging  eero-purulent  fluid,  which  has  a 
very  bad  odor.  This  leg  is  swollen  between  knee  and  ankle;  both  prescapular  glands 
are  enlarged;  vulva  only  slightly  swollen  with  very  little  discharge.  Several  plaques 
on  body. 

May  24.  Has  patch  of  edema  between  forelegs.  Vulva  still  swollen,  and  plaques 
seem  to  be  disappearing. 

May  25.  Vulva  only  slightly  swollen.  A  new  plaque  has  appeared  in  left  inguinal 
region,  and  old  ones  have  not  altogether  disappeared. 

May  29.  One  old  plaque  is  still  present  on  left  side;  others  have  disappeared. 
Abscess  on  knee  still  discharging.     Vulva  still  swollen. 

May  31.  Vulva  is  very  much  swollen.  Left  hind  leg  swollen.  Old  plaque  on  left 
side  is  still  present  and  several  new  ones  have  appeared. 

June  1.  Vulva  much  swollen.  Swelling  on  knee  reduced.  Abscess  still  discharg- 
ing, and  an  extensive  patch  of  edema  on  abdomen. 

June  3.  Has  a  large  amount  of  edema  on  abdomen  and  between  fore  legs.  Abscess 
still  discharging.     Ulcers  on  hocks.     Vulva  still  swollen. 

June  5.  Only  a  small  amount  of  edema  on  abdomen;  abscess  not  discharging;  a 
few  plaques  still  present;  vulva  only  slightly  swollen. 

August  3.  Several  small  plaques  present.     Highest  temperature  recorded,  102.2°  F. 

September  10.  Gave  birth  to  a  healthy  male  colt. 

October  12.  Served  by  male  48  to-day,  and  three  additional  times  since  September 
21,  without  infecting  him. 

May  18.  Killed  to-day.     All  organs  normal. 

Mare  33,  suspected  of  being  in  foal,  was  inoculated  on  November  4, 
1903,  with  material  containing  tiypanosomes  obtained  from  the  dog 
imported  from  France.  Two  inoculations  were  made,  5  c.  c.  being 
used  subcutaneously  in  front  of  left  sboulder  and  5  c.  c.  subcutaneously 
into  the  left  hip. 

Mare  No.  33. 

November  8.  Has  a  soft  sensitive  swelling  about  4  by  6  by  ^  inches  in  size  at  seat 
of  injection  in  front  of  left  shoulder,  and  a  very  flat  sensitive  swelling  about  5  inches 
in  diameter  on  left  hip. 

November  9.  The  swellings  on  hip  and  in  front  of  shoulder  have  become  much 
smaller. 

November  11.  The  swellings  have  increased,  are  hard  and  very  sensitive.  The 
one  in  front  of  left  shoulder  is  about  4  by  5  by  1  inches  in  size,  and  the  one  on  left  hip 
is  about  8  inches  in  diameter  by  ^  inch  high. 

November  12.  The  swellings  are  about  the  same  as  yesterday. 

November  16.  The  swellings  have  almost  disappeared.  No  lesions  to  be  seen 
elsewhere. 

November  20.  The  swellings  have  disappeared. 

December  1.  Has  a  patch  of  edema  about  6  by  8  by  1^  inches  in  size  between  the 
forelegs;  also  has  some  edema  over  the  abdomen .  Udder  enlarged.  Hind  legs  below 
hocks  are  edematous.  No  swellings  at  seats  of  injections.  Animal  seems  to  be  well 
otherwise. 


26  DOURINE   OF   HORSES:   ITS   CAUSE   AND   SUPPRESSION. 

December  2.  Has  a  sharply  defined  patch  of  edema  about  2  inches  high  which 
extends  over  almost  the  entire  sternum  and  abdomen.  The  legs  are  edematous.  No 
lesions  at  seats  of  injections  or  in  vagina.     Animal  seems  to  be  well  otherwise. 

December  3.  Same  as  yesterday. 

December  12.  Edema  about  2^  to  3  inches  in  height  and  extends  over  entire  sternum 
and  abdomen.     No  lesions  to  be  seen  in  vagina.     Animal  otherwise  appears  normal. 

December  15.  No  further  reduction  in  amount  of  edema.     Animal  seems  to  be  well. 

December  23.  Still  has  considerable  edema  over  abdomen. 

December  30.  Has  been  quite  lame  in  left  hind  leg  for  several  days  past.  Edema 
over  the  sternum  is  slowly  disappearing. 

December  31.  The  edema  is  nearly  gone.  Animal  is  still  quite  lame,  but  appetite 
is  fairly  good. 

January  2.  The  edema  has  entirely  disappeared  from  sternum  and  abdomen.  The 
lameness  is  slowly  disappearing  and  health  seems  to  be  good. 

January  6.  Very  lame  in  left  hip;  can  bear  no  weight  on  this  leg,  which  seems  to  be 
very  painful.     Mare  seems  to  be  well  otherwise.     No  lesions  to  be  seen  in  vagina. 

January  8.  Leg  seems  to  be  more  painful  than  ever,  so  much  so  that  she  will  not 
stand  up  long  enough  to  eat  all  of  her  morning  feed. 

January  11.  Seems  unable  to  remain  on  her  feet  but  a  few  minutes  at  a  time,  but 
appetite  is  fairly  good. 

January  12.  Lameness  is  slowly  becoming  worse,  and  right  hind  leg  seems  to  be 
affected  also.  Appetite  seems  to  be  fairly  good,  but  she  does  not  seem  able  to  stand 
on  her  feet  long  enough  to  eat  very  much. 

January  15.  Unable  to  get  up  without  assistance,  and  can  not  stand  owing  to  weak- 
ness in  lumbar  region.     Appetite  is  good.     Mucous  membrane  of  vulva  is  injected. 

January  18.  Mucous  membrane  of  vulva  and  vagina  very  much  congested.  Animal 
imable  to  get  up,  lies  stretched  out  and  seems  to  be  in  considerable  pain,  but  holds 
head  up  to  eat  and  has  considerable  sticky  muco-pm*ulent  vaginal  discharge  which 
contains  a  few  trypanosomes.  Temperatiire  is  commencing  to  rise;  103.2°  F.  at  9 
a.  m.,  103.8°  F.  at  5  p.  m. 

January  20.  Animal  considerably  weaker  than  heretofore;  has  very  little  appetite, 
and  a  profuse  yellowish  discharge  from  vagina,  which  is  still  much  congested.  Rab- 
bits and  rats  inoculated  with  this  discharge  showed  the  presence  of  numerous  trypano- 
somes. 

January  21.  Little  change  since  yesterday,  but  mare  is  weaker. 

January  22.  One  sharply  defined  patch  of  edema  about  4  by  3  by  1  inches  in  size 
on  opposite  side  to  that  on  which  the  animal  is  lying. 

Is  much  weaker  than  she  has  ever  been;  respiration  accelerated;  does  not  take 
notice  of  anything.  Temperature  at  8.30  a.  m.,  105.6°  F.;  at  10  a.  m.,  106°  F.;  at 
1.30  p.  m.,  106.4°  F. 

Has  several  bed  sores  which  have  an  offensive  odor.  Wounds  made  over  jugular 
for  drawing  blood  do  not  heal. 

Found  dead  about  4.20  p.  m. 

The  post-mortem  examination  showed  the  animal  to  have  fallen 
off  gradually  in  flesh.  The  skin  contains  several  bed  sores  involving 
the  adjacent  muscles.  The  heart  is  normal;  left  lung  hypostatic  ally 
congested;  liver  enlarged  and  friable;  kidneys  softened,  pale,  swollen, 
and  contain  a  few  extravasations;  spleen  darkened,  enlarged,  and 
shows  several  petechiae  under  the  capsule;  uterus  contains  an  8- 
months  fetus,  which  is  apparently  normal;  vagina  is  edematous,  with 
a  gelatinous  infiltration  of  the  mucosa;  vulva  appears  swollen  and 
slightly  congested,  with  a  gelatinous  exudate  adhering  to  its  walls. 


SYMPTOMS.  27 

The  left  coxo-femoral  articulation  shows  a  roughened  erosion  on  the 
acetabulum  one-eighth  by  one-third  of  an  inch  in  size,  while  the  head 
of  the  femur  contains  a  similar  ulcerated  area,  which  no  doubt  was  the 
cause  of  the  pain  and  lameness  in  this  leg. 

Many  smear  preparations  were  made  and  various  small  experi- 
mental animals  were  injected  at  different  times  with  material  from 
this  mare,  and  although  the  trypanosomes  were  elusive  and  at  times 
exceedingly  difficult  to  find,  they  nevertheless  were  usually  located, 

SYMPTOMS. 

There  are  many  variations  in  the  symptoms  of  dourine,  and  this  is 
particularly  true  of  the  disease  as  it  occurs  in  this  country.  In  order 
to  give  a  fair  idea  of  the  "symptom  complex"  it  will  be  necessary  to 
describe  manifestations  which  may  appear  in  a  number  of  horses,  it 
being  understood  that  each  individual  may  have  several  but  not  all 
of  the  symptoms  enumerated.  Two  distinct  stages  may  be  noted, 
which  vary  somewhat  from  those  described  in  textbooks,  but  prob- 
ably no  more  than  could  be  expected  w^hen  differences  of  climatic 
conditions  and  methods  of  handling  are  taken  into  consideration. 

The  first  stage  chiefly  concerns  the  sexual  organs,  and  therefore 
differs  somewhat  in  the  male  and  female.  In  the  second  stage  symp- 
toms indicating  an  affection  of  the  nervous  system  are  more  promi- 
nent and  are  not  dependent  on  the  sex  of  the  animal. 

Following  a  variable  period  of  incubation  of  from  eight  days  to 
two  months,  there  is  seen  in  the  stallion  an  irritation  and  swelling 
about  the  penis  first  noticed  in  the  glans.  This  swelling  extends 
throughout  the  organ,  and  the  penis  may  be  continually  protruded 
and  frequent  erections  noticed.  The  edematous  swelling  also 
involves  the  groin,  with  enlargement  of  the  adjacent  inguinal  glands, 
and  extends  forward  along  the  abdomen.  In  a  few  days  small 
vesicles  or  blisters  appear  on  the  penis,  which  break,  discharging  a 
yellowish  serous  fluid  and  leaving  irregular  raw  ulcers.  Where  pri- 
mary ulcers  are  in  proximity  to  each  other  there  is  a  marked  disposi- 
tion to  coalesce,  a  large  raw  surface  with  an  irregular  border  resulting. 
The  ulcerative  process  may  form  a  wound  extending  almost  entirely 
around  the  penis.  The  ulcers  show  a  tendency  to  heal  rapidly, 
leaving  white  cicatrices  or  scars  which  are  permanent.  In  some 
cases  the  urinary  meatus  is  very  red  and  swollen,  and  according  to 
some  observers,  especially  European,  more  or  less  of  a  thick  catarrhal 
exudate  is  discharged  from  its  orifice.  This  condition,  however,  has 
been  rarely  seen  in  cases  in  this  country,  a  more  or  less  continuous 
dripping  from  the  urethra  of  a  yellowish,  serouslike  discharge  alone 
being  present.  The  stallion  retains  his  full  genesic  instinct  and 
becomes  very  amorous  when  brought  in  the  vicinity  of  mares.  If 
allowed  access  to  mares  in  season,  service  is  often  impossible,  due  to 


28  DOUBTNE   OF   HORSES:   ITS   CAUSE   AND   SUPPRESSION. 

the  fact  that  a  complete  erection  of  the  penis  does  not  occur.  The 
testicles  may  be  involved  and  tender  to  pressure,  and  abscess  forma- 
tion may  occur,  with  sloughing. 

In  the  mare  the  first  symptoms  may  be  so  slight  as  not  to  be 
noticed  by  the  owner.  This  is  especially  so  where  the  mares  are 
running  on  the  open  range  and  not  seen  by  the  owner  for  long  periods. 
In  fact,  the  first  knowledge  in  such  instances  frequently  comes  from 
finding  a  diseased  mare  astray  in  the  foothills,  having  been  driven 
out  of  the  band  by  the  stallion.  This  custom  of  getting  rid  of  unde- 
sirable or  diseased  mares  is  quite  general  with  the  leader  of  a  harem 
of  mares  running  at  large  in  distinct  bands  on  the  western  ranges. 
However,  the  disease,  being  the  result  of  copulation,  begins  with 
swelling  and  inflammation  of  the  vulva  and  vagina.  The  labia  are 
continually  everted,  exposing  the  cUtoris,  which  is  constantly  in  a 
state  of  erection.  There  will  also  be  a  muco-purulent  discharge  like 
that  coming  from  the  penis  of  the  male,  which  may  be  slight  or  pro- 
fuse in  quantity,  agglutinating  the  hairs  of  the  tail.  The  mare  will 
switch  the  tail,  appear  uneasy,  and  urinate  frequently.  Shortly 
papules  and  vesicles  appear  on  the  external  vulva,  as  well  as  on  the 
mucosa  of  the  vulva  and  vagina.  These  vesicles  soon  rupture,  but 
before  doing  so  the  contents  undergo  a  change  from  a  transparent 
to  a  purulent  fluid.  The  rupture  of  these  pustules  is  the  initial 
stage  in  the  formation  of  deep,  angry  ulcers.  These  ulcers  show  a 
tendency  to  heal  rapidly,  but  invariably  leave  a  cicatrix,  which  is 
permanent,  causing  a  slight  puckering  of  the  tissue.  On  the  dark 
skin  on  the  external  vulva  the  scars  will  always  be  white,  more  or 
less  circular  in  outline,  from  one-eighth  to  one-half  inch  in  diameter, 
and  pitUke,  similar  to  the  depression  in  a  pockmark.  This  depig- 
mentation of  the  skin  about  the  external  genitals,  due  to  healing  of 
the  ulcer,  is  permanent  and  not  temporary,  as  in  coital  exanthema 
and  other  affections  simulating  it.  Edematous  infiltration  of  the 
perineum  and  the  mammary  gland  frequently  occurs. 

Sometimes,  and  especially  in  the  mare,  the  above-described  lesions 
tend  to  disappear  gradually,  and  in  case  the  mare  is  not  served  again 
the  disease  may  remain  in  abeyance  for  months  or  a  year.  The 
apparent  recovery,  however,  is  not  permanent,  and  any  excessive 
work  or  excitement,  and  especially  being  served  by  a  stallion,  even 
if  he  be  healthy,  may  set  up  the  disease  anew.  In  case  an  affected 
mare  conceives,  she  is  Uable  to  abort  at  any  time  during  her  term  of 
pregnancy.  When  the  fetus  is  carried  to  full  term,  it  occasionally 
is  a  weak  and  imperfectly  developed  foal;  but  in  this  country  many 
fine  colts  have  been  bom  to  affected  mares. 

The  nervous  or  constitutional  disturbances  of  the  second  stage  may 
not  come  on  for  months  or  even  a  year  after  the  appearance  of  the 
local  lesions,  and  are  similar  in  both  male  and  female.     They  consist 


BuL.  142,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  IV. 


ia  5 

Oa  2 

Q  z  o 

li.  <  ^ 
o 


-^.r? 


BuL.  142,  Bureau  of  Animal  Industry,  U.  S.  Dept.  of  Agriulture. 


Plate  V. 


-    ^ 


POST-MORTEM   LESIONS.  29 

of  a  general  nervous  disorder  with  staggering,  swaying  gait,  especially 
in  the  hind  limbs.  The  animal  becomes  extremely  emaciated,  partic- 
ularly in  the  hind  quarters,  and  the  abdomen  assumes  a  "  tucked-up" 
appearance.  (See  PI.  Ill,  fig.  1.)  The  first  indication  of  paralysis 
will  be  noted  in  traveling,  when  the  animal  fails  to  pick  up  one  of 
the  hind  feet  as  freely  as  the  other.  There  is  a  tendency  to  drag  the 
foot  partially,  which  will  wear  off  the  toe  more  than  normal.  This 
condition  may  shift  from  one  hind  foot  to  the  other,  or  both  may 
become  affected  simultaneously,  at  which  time  knuckling  is  a  com- 
mon symptom.  (See  PI.  Ill,  fig.  2.)  Only  occasionally  are  the 
nerves  of  the  front  extremities  and  the  face  affected,  the  latter  find- 
ing expression  in  paralysis  of  an  ear,  eyelid,  nostril,  or  lip.  (See  PI. 
IV,  fig.  1.)  Twitching  of  the  superficial  muscles  has  also  been  noted 
in  several  instances.  Urticarial  eruptions  oc  plaques  may  break  out 
over  various  parts  of  the  body.  These  swellings,  which  prior  to  the 
recent  Iowa  outbreak  had  been  observed  in  only  a  few  cases  in  this 
country,  disappear  in  a  few  days,  only  to  reappear  at  some  other 
point.  In  the  outbreak  just  referred  to  almost  every  horse  showed 
two  or  more  plaques.  They  are  sharply  defined,  round,  flat,  edema- 
tous infiltrations  of  the  papillary  layer  of  the  skin,  about  the  size  of  a 
half  dollar,  or  may  be  even  larger.  Some  have  a  depressed  center 
and  an  elevated  periphery.  When  punctured,  a  bloody  serum  exudes 
from  the  cut  surface.  The  usual  locations  of  these  plaques  are  the 
croup,  belly,  and  neck,  (See  PI.  V.)  There  may  also  be  noted 
pruritis  of  the  skin,  which  causes  the  animal  to  rub  itself  fre- 
quently. White  spots  appear  on  the  hind  legs  and  in  the  region  of 
the  perineum,  as  a  result  of  the  discharge  from  the  penis  and  vagina 
coming  in  contact  with  and  causing  a  depigmentation  of  the  integu- 
ment. (See  PL  IV,  fig.  2.)  The  temperature  of  the  animal  seldom 
goes  above  101°  or  102°  F.  Labored  breathing  is  occasionally  noted. 
In  some  cases  the  glands  under  the  jaw  swell  and  a  discharge  appears 
from  the  nostril  simulating  glanders.  When  the  paralysis  of  the  hind 
limbs  starts  to  appear,  it  usually  progresses  rapidly,  the  horse  goes 
down,  is  unable  to  rise,  and  dies  in  a  short  time  from  nervous  exhaus- 
tion. Up  to  the  last,  however,  the  appetite  remains  good,  and  the 
stallion  will  show  a  desire  for  the  mare,  although  service  is  impossible, 
as  the  horse  can  neither  get  a  complete  erection  nor  raise  himself  on 
his  hind  legs. 

POST-MORTEM  LESIONS. 

On  autopsy  there  are  noted  swelling  and  gelatinous  infiltration  of 
the  mucosa  of  the  vulva  and  vagina,  together  with  marked  hyperemia. 
The  uterine  mucosa  is  thickened,  infiltrated,  and  corrugated,  resem- 
bling tlie  mucous  membrane  of  the  large  intestine  in  Johne's  disease. 
Ulcers  are  sometimes  present,  although  rarely  so  in  the  disease  as  it 


30  DOURINE   OF   HORSES:   ITS  CAUSE   AND   SUPPRESSION. 

exists  in  this  country.  The  mucous  membrane  is  not  infrequently  of 
an  orange-colored  hue,  covered  with  a  muco-purulent  exudate  and 
occasionally  supports  small,  irregular  yellowish  patches  of  mucoid 
degeneration.  The  ovaries  are  frequently  involved,  and  their  paren- 
chyma may  be  the  seat  of  hemorrhage  and  large  blood  clots  may  be 
found  within  their  capsules.  The  skin  in  the  region  of  the  perineum 
where  the  discharge  has  come  in  contact  with  it  is  depigmented, 
leaving  irregular  white  patches.  In  the  male  the  penis  is  usually 
found  to  be  enlarged,  although  in  some  cases  it  is  normal  in  size.  It 
frequently  contains  ulcers  and  scar  tissue  both  on  its  surface  and  in 
urethral  canal.  The  sheath  is  also  tumefied  and  the  skin  thickened. 
The  testicles  in  some  cases  are  soft  and  atrophied,  while  in  others  just 
the  opposite  is  found.  Adhesions  may  occur  between  the  tunica 
vaginalis  and  the  tunica  propria.  In  nearly  all  cases  the  scrotum  is 
more  or  less  infiltrated.  The  lymphatic  glands  in  the  inguinal  region 
are  also  inflamed,  and  in  many  cases  may  be  plainly  visible  as  irregular 
wavy  lines  under  the  skin.  There  is  also  a  yeUow  gelatinous  exudate 
beneath  the  skin  in  those  areas  where  plaques  were  situated  just 
before  death.  In  cases  of  long  duration  there  is  more  or  less  marked 
atrophy  of  .the  muscular  system,  a  condition  naturally  following  the 
paralysis  which  precedes  death. 

The  changes  in  the  spinal  cord  have  been  principally  studied  by 
Thanhoffer.  The  meninges,  especially  the  pia  mater,  are  severely 
congested;  in  some  places  adhesions  have  taken  place  between  the 
pia  and  the  cord,  while  in  others  the  pia  is  severely  congested.  The 
central  canal  in  the  spinal  cord  is  dilated  in  certain  points  and  may 
contain  an  excessive  quantity  of  fluid.  On  section  softened  areas 
may  be  found  in  the  substance  of  the  cord,  and  dark  red  spots  may 
also  be  present,  indicating  hemorrhage.  The  supporting  framework 
of  the  spinal  cord  (neuroglia  tissue)  is  hypertrophied,  especially 
around  the  central  canal,  producing  sclerosis,  or  hardening  of  the  cord. 
The  large  spinal  nerve  cells  are  involved,  and  the  nuclei  frequently 
undergo  granular  disintegration.  In  other  cells  the  axicyUnder  pro- 
cess is  affected  and  its  outline  is  wavy  and  tortuous.  According  to 
Marek,  the  change  observed  in  the  nerves  is  a  polyneuritis.  The 
ventricles  of  the  brain  also  contain  an  excessive  amount  of  fluid. 
In  summarizing,  we  may  say  that  there  is  a  general  hydrops  of  the 
central  nervous  system  with  a  tendency  to  degeneration  in  the  spinal 
cord,  and  multiple  hemorrhage  formation  in  the  substance  of  the 
cord  with  slight  leucocytic  infiltration.  The  skeleton  is  also  affected, 
and  the  bones  may  be  softened.  The  medullary  substance  (marrow) 
is  congested,  and  hemorrhages  and  erosions  may  be  seen  on  the 
articular  cartilages  of  the  joints.  A  discoloration  of  the  synovia,  due 
to  red  blood  cells,  is  frequently  seen,  giving  it  a  peculiar  pinkish 
coloration. 


COURSE   OF   THE   DISEASE PROGNOSIS.  31 

The  intestines  usually  contain  but  small  quantities  of  alimentary 
matter,  and  ulcers  may  sometimes  be  found  in  the  mucous  membrane. 
The  peritoneum  is  hypertrophied  and  has  a  yellowish  cast,  due  to 
the  serum  it  contains  in  its  meshes.  The  mesenteric  and  inguinal 
lymph  glands  may  be  enlarged  and  softened  or  small  and  firm  in  con- 
sistency. The  liver  contains  areas  of  fatty  degeneration,  is  severely 
congested,  and  may  contain  minute  hemorrhages  in  its  parenchyma. 
The  spleen  may  also  contain  these  petechia,  but  it  is  usually  only 
slightly  enlarged,  soft,  and  doughy,  although  it  may  be  normal  in 
size  and  appearance  in  the  horse.  In  experimental  animals,  how- 
ever, and  particularly  white  rats  inoculated  with  trypanosomes, 
this  organ  is  enlarged  to  two  to  three  times  the  normal  and  very 
severely  congested. 

The  kidneys  are  enlarged  and  soft  in  consistency  and  show  the 
presence  of  parenchymatous  degeneration.  The  lungs  are  almost 
invariably  very  much  congested,  and  suppurative  foci  may  some- 
times be  found  in  their  substance.  The  blood  is  watery  and  forms 
imperfect  soft  clots,  the  red  blood  cells  having  undergone  extreme 
.diminution  in  number,  although  there  is  a  decided  leucocytosis  with 
a  marked  increase  in  the  quantity  of  lymphocyte  cells. 

COURSE  OF  THE  DISEASE. 

The  course  of  the  disease,  as  will  be  seen  from  the  symptoms,  is 
extremely  variable,  and  may  cover  a  period  ranging  from  nine 
months  to  two  years.  At  the  commencement  of  the  attack  the 
genital  symptoms  alone  are  observable.  These,  however,  sooner  or 
later  become  complicated  by  the  appearance  of  the  systemic  or 
nervous  disturbances,  including  loss  of  flesh,  staggering  gait,  and 
paralysis  of  the  posterior  extremities.  These  symptoms  gradually 
become  intensified  until  the  animal,  reduced  to  skin  and  bone,  is 
unable  to  rise,  and  death  at  last  results  from  exhaustion,  lack  of 
nutrition,  or  from  septic  infection.  This  course  is  markedly  influ- 
enced by  the  condition  and  environment  to  which  the  animal  has  been 
subjected.  Bad  weather,  exposure,  insufficient  food,  and  compli- 
cating diseases  like  influenza,  distemper,  or  in  fact  any  condition 
which  tends  to  lower  the  vitality  of  the  animal,  will  hasten  the 
termination  of  the  disease.  On  the  other  hand,  good  care  and 
abundant  food  will  prolong  life,  and  in  this  country  has  even  resulted 
in  recovery.  It  is  also  possible  under  favorable  conditions  that  an 
animal  may  have  dourine  in  the  latent  form  for  several  years  without 
manifesting  any  alarming  symptoms  and  yet  be  a  source  of  danger. 

PROGNOSIS. 

Although  now  and  then  a  case  of  dourine  may  recover,  as  a  rule 
the  disease  is  present  merely  in  a  latent  state,  and  the  excitement 


82  DOURINE   OF   HORSES:  ITS  CAUSE  AND   SUPPRESSION. 

caused  by  copulation  is  very  likely  to  cause  it  to  reappear  with 
renewed  vigor.  The  outlook,  therefore,  from  a  prognostic  pomt  is 
always  to  be  considered  unfavorable,  and  in  a  country  where  a  rela- 
tively small  number  of  cases  appear  temporizing  methods  of  suppress- 
ing the  disease  are  not  warranted. 

DIFFERENTIAL  DIAGNOSIS. 

In  countries  where  dourine  is  the  only  infection  caused  by 
trypanosomes,  the  diagnosis  is  made  certain  by  the  demonstration 
of  these  parasites;  but,  as  has  already  been  noted,  this  is  connected 
with  considerable  difficulty,  as  the  parasites  in  the  blood  appear  very 
seldom  and  then  only  in  small  numbers.  They  are  most  constant 
in  the  serous  fluid  of  the  cutaneous  plaques  and  in  the  edematous 
swellings  and  muco-purulent  discharges  of  the  vagina,  but  even  here 
they  appear  only  periodically.  While  it  is  a  comparatively  easy 
task  to  diagnose  the  disease  in  its  acute  form  if  ulcers  are  present  on 
the  genitals  and  edematous  patches  on  the  skin,  those  cases  which 
have  apparently  recovered,  or  which  may  more  properly  be  termed 
chronic,  present  many  difficulties.  The  diagnosis  is  much  easier  it 
several  animals  are  affected  at  the  same  time. 

Coital  exanthema  or  vesicular  exanthema  is  the  disease  most  fre- 
quently mistaken  for  dourine,  as  both  appear  shortly  after  the  act  of 
copulation  with  nearly  similar  symptoms.  During  the  ulcerative 
stage  and  without  a  history  of  the  case,  it  is  somewhat  difficult  to 
make  a  differential  diagnosis.  However,  the  period  of  incubation  in 
coital  exanthema  is  shorter,  the  ulcers  produced  by  the  ruptured 
vesicles  are  more  superficial  and  heal  more  rapidly,  the  resulting 
depigmention  is  only  temporary,  and  permanent  scars  on  the  mucosa 
of  the  genitals  are  not  observed,  neither  does  it  cause  abortion  or 
terminate  in  paralysis. 

At  times  the  initial  stage  of  dourine  is  confounded  with  a  traumatic 
inflammation  of  the  genital  organs.  However,  the  traumatic  origin 
may  easily  be  excluded,  on  the  one  hand,  through  the  lack  of  observ- 
able lesions;  and,  on  the  other,  through  the  character  and  persistent 
continuance  of  the  edematous  swelling. 

The  plaques  of  dourine  are  similar  to  urticaria,  but  in  the  latter 
disease  lesions  of  the  genital  tract  and  nervous  symptoms  are  absent, 
and  there  is  no  evidence  of  contagion. 

The  paralysis  of  the  hind  quarters  is  only  characteristic  for  dourine 
when  taken  in  connection  with  other  nervous  symptoms.  Among 
other  diseases  showing  a  similar  paralysis  may  be  mentioned  azoturia, 
forage  poisoning,  and  swamp  fever,  but  these  diseases  are  as  likely  to 
affect  geldings  as  stallions  or  mares.  They  may  also  be  discriminated 
from  the  paralysis  of  dourine  mainly  through  the  absence  of  lesions 


DIFFERENTIAL  DIAGNOSIS.  33 

of  the  sexual  organs.  In  the  latter  disease  the  accessory  conditions, 
such  as  the  infection  of  several  animals  shortly  after  the  act  of  copu- 
lation, as  well  as  the  different  aspect  of  the  symptoms  in  the  affected 
animals,  offers  a  sufficient  foundation  for  a  correct  diagnosis. 

Although  the  vaginal  discharge  of  leucorrhea  may  resemble  that  of 
dourine,  the  characteristic  ulcer  or  cicatrix  of  dourine  is  always 
absent.  The  nearest  approach  to  it  is  a  raw  and  abraded  condition 
of  the  lips  of  the  vulva  due  to  the  irritating  properties  of  the  discharge. 
Nervous  symptoms  terminating  in  paralysis  are  not  observed. 

On  the  western  range  it  is  not  unusual  to  see  several  stallions 
ranging  with  a  small  band  of  mares.  This  is  especially  so  on  the 
Indian  reservations,  where  in  several  cases  as  high  as  40  per  cent  of 
the  band  were  stallions.  Under  such  conditions  a  mare  during  the 
period  of  heat  is  served  repeatedly.  The  vaginal  mucous  membrane 
becomes  a  livid  red  and  slight  abrasions  are  not  uncommon.  If  exam- 
ined shortly  after  the  subsidence  of  the  period  of  heat  the  vaginal 
mucosa  will  present  a  mottled  variegated  appearance,  being  red, 
dark  red,  and  even  purple  in  patches. 

In  the  alkah  districts  during  hot  weather  it  is  not  uncommon  to 
see  horses  with  extensive  chafing  between  the  thighs,  in  the  folds  of 
skin  on  either  side  of  the  vulva,  or  on  the  loose  folds  of  the  sheath, 
as  a  result  of  the  natural  secretions  mixed  with  alkali  dust.  Exten- 
sive depigmentation  of  the  affected  area  is  the  result.  Such  depig- 
mented areas  and  those  resulting  from  abrasions  or  lacerations  are 
irregular  in  outline  and,  unless  from  a  deep  laceration,  are  not  per- 
manent, whereas  those  due  to  dourine  are  usually  circular  in  outline, 
cicatricial  in  character,  and  permanent.  Natural  depigmented  areas 
are  common  in  the  so-called  "Arabian"  horses  of  the  western  range 
and  in  those  animals  with  an  admixture  of  the  blood  of  the  pinto 
pony,  a  species  of  equine  albino  very  popular  among  the  Indians. 

Ulcers  on  the  mucosa  of  the  genitals  may  be  mistaken  for  glanders, 
especially  when  the  lymph  vessels  and  lymph  glands  are  simultane- 
ously inflamed.  In  this  case  the  further  progress  of  the  disease, 
serum  diagnosis,  mallein  test,  or  inoculation  experiments  will  fur- 
nish definite  diagnostic  information. 

Dourine  may  also  be  mistaken  for  surra  in  countries  where  the 
latter  disease  prevails,  but  as  surra  does  not  exist  in  the  United  States, 
it  need  not  be  considered  from  a  differential  standpoint  in  this 
country. 

Phlegmonous  inflammation  and  pyemic  abscesses,  with  swelling  of 
the  adjacent  lymph  glands,  may  sometimes  occur  after  copulation  in 
mares  and  stallions  which  are  suffering  from  an  ichorous  purulent 
discharge,  but  the  absence  of  further  progress  of  the  condition  will 
easily  decide  the  diagnosis. 


34  DOURiNE  OF  horses:  its  cause  and  suppression. 

Melanotic  tumors  appearing  about  the  anus  and  vulva  of  gray 
horses  and  carcinoma  of  the  penis  have  been  the  cause  of  several 
inspections  for  suspected  dourine,  but  they  should  never  be  mis- 
taken for  lesions  of  dourine  by  anyone  in  the  least  familiar  with  this 
disease. 

TREATMENT. 

Little  benefit  can  be  obtained  from  the  medicinal  treatment  of 
this  chronic  malady,  nor  is  such  treatment  desirable  in  this  country, 
where  the  disease  has  existed  only  in  restricted  areas  and  where 
sanitary  considerations  demand  its  prompt  extirpation.  Some  cases, 
however,  have  been  observed  where  improvement  and  recovery  fol- 
lowed local  treatment  when  applied  in  the  early  stages  of  the  infec- 
tion. When,  however,  any  systemic  symptoms  appear,  drugs  seem 
to  be  useless  and  deaths  follow  after  very  varying  periods  of  time  in 
different  cases. 

As  the  infection  takes  place  through  the  genital  apparatus,  the 
thorough  application  to  these  parts  of  antiseptic  solutions  with  the  idea 
of  destroying  the  trypanosomes  before  they  obtain  access  to  the  gen- 
eral circulation  may  be  looked  upon  as  the  most  rational  treatment. 
This,  although  practicable  in  the  male,  is  extremely  difficult  to 
accomplish  thoroughly  in  the  female.  Toward  this  end  corrosive 
sublimate,  1  to  2,000,  or  2  per  cent  solution  of  carbolic  acid  or  creolin, 
should  be  injected  into  the  vagina  of  the  mare  and  the  sheath  and 
penis  of  the  stallion  immediately  upon  the  first  appearance  of  inflam- 
mation of  the  genitals  following  the  act  of  coition  in  infected  localities, 
or  where  for  any  reason  the  presence  of  the  disease  is  to  be  suspected. 

After  the  systemic  symptoms  of  urticarial  eruption  and  paresis 
with  rapid  loss  of  flesh  in  spite  of  a  good  appetite  begin  to  appear, 
the  symptomatic  treatment  with  stimulants  and  alteratives  has  been 
recommended,  but  is  of  very  slight  value  except  to  prolong  the  life 
of  the  patient.  Among  such  drugs  may  be  mentioned  strychnin  (1 
grain  three  times  daily)  or  potassium  iodid  (2  to  5  drams  daily)  for 
their  alterative  action.  Marchal,  of  the  remount  depot,  Constantine, 
Algeria,  reports  on  the  treatment  of  six  stallions  with  cacodylate  of 
soda,  1  gram  in  5  c.  c.  of  distilled  water,  given  in  two  doses  daily 
subcutaneously  for  five  consecutive  days  with  seven  days  interval, 
while  others  have  recommended  atoxyl,  and  recently  Meissner  has 
been  experimenting  with  arsenophenylglyzin.  Although  the  statis- 
tics of  these  lines  of  treatment  are  very  limited,  they  seem  to  give 
very  promising  results  and  at  least  deserve  further  trial  in  those 
foreign  countries  where  the  disease  is  indigenous. 

During  the  course  of  treatment  care  should  be  taken  not  to  excite 
the  sexual  ardor  of  the  patient,  as  this  under  all  circumstances  aug- 
ments the  symptoms,  and  indeed  the  act  of  copulation,  in  the  mare 
especially,  may  revive  the  symptoms  of  the  disease  in  the  acute 


METHOD   OF   EBADICATION.  35 

stage  when  to  all  external  appearances  the  animal  had  recovered 
from  a  previous  infection. 

METHOD  OF  ERADICATION. 

Sanitary  measures  looking  to  the  eradication  of  dourine  must 
depend  on  the  principle  that  horses  infected  with  dourine  should  be 
excluded  from  breeding.  This  action  is  well  founded,  for,  in  spite  of 
the  possibihty  of  cure,  there  are  as  a  matter  of  fact  frequent  relapses, 
and  further,  trypanosomes  may  exist  for  months  in  the  sexual  organs 
of  the  apparently  cured  animal.  Therefore,  it  is  very  essential  to 
destroy  the  diseased  mares  and  to  castrate  the  affected  stallions. 
The  objection  to  spaying  mares  is  that  if  they  should  be  sold  and 
attempt  to  breed,  the  disease  may  be  contracted  by  the  serving 
stallion  and  thus  spread.  On  the  other  hand,  staUions  which  are 
castrated  before  the  appearance  of  paralytic  symptoms  become  sound 
and  well,  but  the  stallions  even  after  castration  will  frequently  serve 
mares.  They  should  therefore  be  prevented  from  mingling  with 
mares  for  a  month  after  the  ulcers  are  healed. 

Dourine,  being  conveyed  solely  by  coitus,  is  not  a  difficult  disease 
to  stamp  out  in  a  farming  community  such  as  in  Illinois,  where  the 
first  outbreak  occurred,  or  in  Iowa,  where  the  infection  appeared  in 
1903  and  1911.  But  when  the  disease  reached  the  open  range  and 
infected  horses  which  ran  in  thei  foothills  and  "bad  lands "  of  Nebraska 
and  South  Dakota,  respectively,  the  difficulties  increased  manyfold, 
as  inspections  in  many  cases  could  be  made  only  at  the  spring  round- 
up. Even  then  there  were  but  frequently  but  60  to  70  per  cent  of 
the  horses  gathered  up,  owing  to  the  rough  condition  of  the  land  and 
the  impossibiUty  of  seeing  the  stray  animals. 

After  mature  consideration  a  definite  poUcy  was  decided  upon 
which  consisted  in  the  slaughter  of  diseased  mares,  castration  or 
slaughter  of  diseased  stallions,  castration  or  quarantine  of  exposed 
stallions,  and  the  frequent  reinspection  of  exposed  mares.  It  was 
further  decided  to  keep  a  sufficient  number  of  men  in  the  infected 
districts  to  carry  out  this  policy,  and  Dr.  E.  T.  Davison  was  placed 
in  charge  of  the  work  of  eradication  with  headquarters  at  Rushville, 
Nebr.  To  his  capable  and  energetic  efforts  must  be  largely  credited 
the  satisfactory  results  which  have  been  accomplished. 

With  the  view  of  preventing  the  shipment  of  diseased  animals 
from  the  infected  districts  the  Secretary  of  Agriculture  issued  an 
order  under  date  of  January  20,  1903,  prohibiting  the  transportation 
or  movement  of  any  horses  in  the  counties  of  Dawes,  Boxbutte, 
Sheridan,  and  Cherry,  in  the  State  of  Nebraska,  and  in  the  Pine 
Ridge  and  Rosebud  Indian  Reservations  and  the  counties  of  Custer 
and  Fall  River,  S.  Dak.,  to  any  other  State  or  Territory  or  the  District 
of  Columbia,  unless  first  inspected  by  an  inspector  of  this  bureau 
and  accompanied  by  a  certificate  issued  by  the  said  inspector. 


36  DouEiNE  OF  horses:  its  cause  and  suppression. 

On  March  10,  1903,  the  Secretary  of  Agriculture,  with  the  con- 
currence of  the  Secretary  of  the  Interior,  issued  an  order  which  was 
posted  throughout  the  above-named  Indian  reservations  prohibiting 
any  stalUon  or  stalUons  from  running  at  large  witliin  the  bounds  of 
these  reservations,  also  directing  that  any  uncastrated  male  horse 
1  year  of  age  or  older  found  running  on  the  range  or  at  large  in  these 
reservations  be  castrated,  and  that  all  stallions  belonging  to  owners 
living  on  Wliito  Clay  Creek,  or  within  1  mile  thereof,  should  be  either 
castrated  or  kept  under  close  quarantine  until  further  orders;  also 
prohibiting,  furthermore,  the  breeding  of  horses  in  herds  in  which 
diseased  animals  had  been  found,  under  any  circumstances,  whether 
in  fenced  pastures,  inclosures,  or  otherwise;  and  directing,  with  a 
provision  for  appraisement  and  indemnity  to  owners,  that  any  animal 
or  animals  showing  symptoms  of  dourine  or  known  to  have  been 
exposed  to  the  disease  should,  in  the  discretion  of  an  inspector  or 
employee  of  the  Department  of  Agriculture,  be  immediately  quar- 
antined, and  maintained  in  quarantine  at  the  expense  of  the  owner 
or  owners  until  released  by  the  inspector  or  condemned  and  slaugh- 
tered. A  statement  was  also  included  to  the  effect  that  any  person, 
company,  or  corporation  knowingly  violating  the  provisions  of  this 
order  would  be  guilty  of  a  misdemeanor,  and  on  conviction  liable  to 
a  fine  of  not  less  than  $100  nor  more  than  $1,000,  or  to  imprisonment 
not  more  than  one  year,  or  to  both  such  fine  and  imprisonment. 

As  a  result  of  the  thoroughness  of  method  followed  in  the  pros- 
ecution of  this  work,  all  the  diseased  animals  in  Nebraska  were  soon 
detected  and  either  destroyed  or  castrated.  But  cases  continued  to 
appear  on  the  Pine  Ridge  Reservation  with  disconcerting  frequency 
as  a  result  of  the  many  difficulties  attendant  upon  range  inspection. 
With  a  view  of  handling  this  work  of  eradication  to  better  advan- 
tage, a  number  of  veterinarians,  including  the  writer  of  tliis  paper, 
were  sent  to  the  Pine  Ridge  Indian  Agency  in  June,  1903,  for  the 
purpose  of  making  inspections  at  the  time  of  the  annual  round-up. 
Inspection  camps  were  estabhshed,  one  veterinarian  and  an  expe- 
rienced roper  being  assigned  to  each  of  the  five  districts  on  the  res- 
ervation— Wakpamini,  White  Clay,  Porcupine,  Wounded  Knee,  and 
Medicine  Root.  All  the  animals  were  rounded  up  in  each  district, 
and  all  diseased  mares  as  well  as  affected  stallions,  wliich  were  of  the 
inexpensive  broncho  type,  were  purchased  and  killed,  while  the 
healthy  staUions  were  castrated  unless  the  owner  agreed  to  keep  the 
animal  off  the  open  range.  In  this  case  the  stalHon  was  tagged  and 
kept  quarantined  on  the  premises.  The  five  round-up  parties  grad- 
ually worked  toward  Pass  Creek,  where  the  final  round-up  took  place. 
At  this  time  all  animals  which  estrayed  from  one  district  to  the  other 
during  the  year  were  returned  and  animals  which  strayed  in  from 
the  adjacent  sections  of  Nebraska  and  South  Dakota  were  claimed 
by  owners  and  removed  by  them  after  inspection.     This  arrangement 


METHOD   OF   ERADIOATION.  37 

made  possible  the  inspection  of  practically  all  the  horses  running  at 
large  on  those  ranges.  Thus  the  advantages  to  be  gained  were 
numerous,  and  large  numbers  of  animals  which  habitually  ran  at 
large  on  the  open  range,  a  great  majority  of  which  had  never  been 
handled,  were  subjected  almost  at  the  same  time  to  careful  veterinary 
examination,  as  in  the  case  of  those  usually  kept  in  barns  or  inclosed 
pastures. 

During  the  round-up  season  from  June  1  to  June  30,  1903,  9,455 
horses  were  examined;  173  were  slaughtered  because  of  showing 
evidences  of  the  disease,  6  of  wliich  were  stallions  and  167  mares. 
In  addition,  1,270  stalUons  running  at  large,  these  being  the  most 
effective  spreaders  of  the  disease,  were  castrated,  and  185  stallions  to 
be  used  for  breeding  purposes  were  tagged  for  identification.  During 
the  year  the  total  number  of  animals  inspected  was  16,287;  number 
found  diseased  and  slaughtered,  511;  number  quarantined  as  sus- 
picious, 277;  number  of  stallions  castrated,  1,889.  The  average 
price  paid  by  the  department  for  animals  slaughtered  because  of 
being  diseased  was  $17.52.  Castrations,  having  been  performed  by 
employees  of  the  bureau,  incurred  no  expense,  and  because  of  this 
operation  the  probability  of  the  transmission  of  the  disease  through 
the  animal  operated  on  was  removed.  Some  of  the  Indian  owners 
objected  strenuously  to  the  castration  of  their  pinto  stalHons,  but  as 
a  rule  very  little  opposition  was  met  from  them,  although  many 
regretted  the  prospects  of  only  a  few  "papoose  ponies"  the  following 
season.  All  stallions  left  for  breeding  purposes  were  tagged  with  a 
quarantine  tag,  kept  under  quarantine  restrictions,  and  regularly 
inspected,  so  that  should  the  disease  develop  at  any  point  it  could 
be  promptly  detected  and  stamped  out.  This  same  systematic 
policy  was  followed  during  the  next  few  years  in  this  section. 

Notwithstanding  the  subsequent  failure  of  any  cases  to  appear, 
constant  vigilance  was  kept  over  the  horses  in  the  infected  sections 
to  make  sure  that  none  of  the  contagion  persisted.  In  order  to  make 
it  an  incentive  to  report  any  diseased  animals  which  might  have  been 
hidden  by  owners,  an  order  was  issued  by  the  Secretary  of  Agriculture 
on  April  15,  1907,  offering  a  reward  of  $50  for  authentic  information 
leading  to  the  discovery  of  the  ownership  and  location  of  a  stallion  or 
a  jack  affected  with  dourine,  and  the  sum  of  $25  for  similar  informa- 
tion leading  to  the  discovery  of  a  female  animal  affected  with  the 
disease  in  the  quarantmed  district,  provided  that  when  more  than 
one  diseased  animal  should  be  found  belonging  to  the  same  owner, 
or  on  the  same  premises,  only  one  reward  should  be  paid.  This 
reward  was  offered  in  addition  to  the  usual  compensation  to  the 
owner.  Notwithstanding  that  this  order  has  been  in  force  since  1907, 
not  one  case  of  dourine  has  been  found  in  that  district,  and  conse- 
quently no  reward  has  ever  been  claimed.      Numerous  suspected 


38  DOURINE   OF   HORSES:   ITS  CAUSE  AND   SUPPRESSION. 

cases,  however,  have  been  reported  from  time  to  time  since  1906  in 
different  sections  of  the  country  by  veterinarians  and  horsemen,  but 
with  tlie  exception  of  the  recent  Iowa  cases  they  have  been  shown  on 
investigation  to  have  been  some  other  disease  simulating  dourine  in 
some  particulars,  and  usually  proving  to  be  coital  exanthema. 

Investigations  have  been  made  in  various  parts  of  South  and  North 
Dakota,  Nebraska,  the  Indian  reservations,  Washington,  Oregon, 
Wyoming,  Oklahoma,  Utah,  and  Montana.  A  careful  inspection  has 
also  been  made  of  the  range  horses  in  some  of  the  principal  range 
States,  several  thousand  animals  having  been  inspected  in  such 
States  in  the  round-up  work,  with  the  assistance  of  veterinary 
inspectors  engaged  in  other  lines  of  field  service,  such  inspections 
having  been  made  for  the  detection  of  scabies,  glanders,  and  dourine. 
The  general  method  has  been  to  have  the  horses  in  any  section  of  the 
country  that  has  ever  been  regarded  with  suspicion  rounded  up 
during  the  breeding  season  and  examined.  In  the  States  of  Montana 
and  Wyoming  the  horses  on  the  Indian  reservations  have  Ukewise 
been  examined,  not  because  of  disease  having  been  reported  among 
the  Indians'  horses  in  these  States,  but  because  of  the  fact  that  if 
there  were  any  disease  in  the  country  the  conditions  prevaiUng  on 
the  Indian  reservations  would  be  likely  to  furnish  an  ideal  medium 
for  its  development  and  dissemination.  For  many  years  the  Crows, 
Arapahoes,  Sioux,  and  Shoshones  have  journeyed  back  and  forth  in  the 
fall  of  the  year  between  the  Sioux  Reservation  at  Pine  Ridge  and  the 
Wind  River  Reservation  in  central  Wyoming  and  the  Crow  Reservation 
in  southern  Montana.  It  is  their  custom  to  leave  some  of  their  horses 
as  gifts  to  their  friends,  and  it  was  the  possibility  that  some  of  these 
animals  might  have  been  affected  with  dourine  that  caused  such 
careful  inspections  to  be  made  at  the  neighboring  Indian  reservations. 
Representative  herds  of  range  horses  have  likewise  been  examined, 
even  when  such  herds  have  never  been  regarded  as  suspicious,  and  all 
herds  that  were  ever  regarded  with  suspicion  were  kept  under  sur- 
veillance for  several  years. 

In  the  eradication  of  a  disease  like  dourine,  especially  when  it  is 
confined  to  a  relatively  small  area,  compensation  for  the  affected 
animals  destroyed  has  a  very  wholesome  influence  on  the  owner  in 
inducing  him  to  notify  the  proper  authorities  of  the  presence  of 
suspected  cases  of  the  disease.  In  many  instances  the  diseased 
animals  are  capable  of  doing  some  work,  and  unless  they  are  bred 
there  is  no  danger  to  other  animals  from  them.  It  is  this  danger 
of  being  bred  which  makes  it  essential  that  they  should  be  destroyed. 
The  existence  of  this  disease  is  a  great  menace  to  the  horse  industry, 
and  speedy  eradication  wherever  it  is  discovered  is  therefore  very 
important. 

o 


